Answer:
It would take 200,000 years for a spaceship traveling at the speed of light to go across the entire galaxy.
The number of periods/series in Mendeleev's Periodic table is
A. 10
B. 13
C. 12
D. 14
Answer: The number of series in Mendeleev's Periodic table is 12.
Explanation:
Horizontal rows present in the periodic table are called periods. Vertical rows in the periodic table are called series.
Mendeleev gave periodic table in the year 1869 by arranging elements according to their atomic weights a in tabular form.
Mendeleev's periodic table depicts 12 periods/series.
Thus, we can conclude that the number of periods/series in Mendeleev's Periodic table is 12.
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Increasing the temperature of a chemical reaction usually increases greatly the rate of the reaction. The most iportant reason for this is that increasing the temperature increases: _______.
A) the collision frequency
B) the probability factor
C) the fraction of collisions with energy greater than Bact
D) the energy of activation.
E) the amount of heat released in the reaction
Answer:
the fraction of collisions with energy greater than Eact
Explanation:
The activation energy of a reaction stands as a sort of energy barrier between reactants and products. It is only reactants that possesses energy greater than the activation energy that can be converted from reactants to products.
When the temperature of the system is increased, more particles acquire energy greater than the activation energy. Hence, the fraction of collisions with energy greater than the activation energy increases so the rate of reaction increases likewise.
How much cesium (half-life = 2 years) would remain from a 10 g sample after
6 years?
O A. 59
O B. 119
O c. 2 1 2
O D.09
Answer:
The correct answer is A. 59.
Explanation:
The formula for finding the amount of radio active substance that remains after decomposition is A = N(1/2) ^y, where A is the mass remaining, N is the original mass of a radioactive sample and y is the number of half life. In this case, N = 10 g and y = 6/2 = 3. So A is given by 10 x (1/2)^3, which is 10 x 1/2 x1/2 x 1/2 = 1.25 grams.
All --- is a good conductor of heat
Determine the molarity of the sodium ions when 78.0 g Na2S is dissolved in water for a final volume of 1.0 L.
Answer:
[Na⁺] = 1.99 M
Explanation:
Na₂S is a ionic salt that can be dissociated.
Dissociation equation is:
Na₂S → 2Na⁺ + S⁻²
1 mol of sodium sulfide can give 2 moles of sodium cation.
We convert moles of salt: 78 g . 1mol / 78.06 g = 0.999 moles
As ratio is 1:2, after dissociation we have (0.999 . 2) = 1.998 moles of Na⁺
Molarity is a type of concentration.
It indicates moles of solute in 1 L of solution and in this case, we have 1 L as final voulme.
Moles of Na⁺ are 1.998 moles. Then molarity (mol/L) is:
M =1.99 mol/L
Identify the statements that correctly describe the saturation temperature of a solution.
A. Any temperature at which the solution is liquid.
B. Any temperature at which all of the compound is solid.
C. The temperature at which solid begins to appear from a cooled solution.
D. The temperature at which the Ksp value can be calculated.
A calorimeter measures the ______ involved in reactions or other processes by measuring the ______ of the materials _____ in the process. The calorimeter is _______ to prevent transfer of heat to outside the device.
Answer:
heat; temperature; surrounding; insulated.
Explanation:
A calorimeter can be defined as a scientific instrument or device designed and developed for measuring the heat involved in reactions or other processes, especially by taking the measurement of the temperature of the materials surrounding the process.
Basically, a calorimeter is insulated using materials with very high level of resistivity so as to prevent heat transfer to the outside of the device (calorimeter). Some of the components that make up a simple calorimeter are thermometer, an interior styrofoam cup, an exterior styrofoam cup, cover, etc.
Additionally, a calorie refers to the amount of heat required to raise the temperature of a gram of water by one degree Celsius (°C).
Which of the following molecules can be used in catabolic reactions to generate the carbon backbones required for gluconeogenesis?
a. glutathione, a short peptide containing glutamate, serine and histidine
b. butyrate, a short chain fatty acid
c. fructose, a monosaccharide
d. starch, a polysaccharide
Answer:
The correct option is A
Explanation:
Some amino acids, called glucogenic amino acids, when catabolized convert there carbon backbones to tricarboxylic acid (TCA) cycle intermediates. These intermediates can be subsequently metabolized into carbon dioxide and water with the release of ATP or the formation of glucose (known as gluconeogenesis.
All amino acids (with the exception of leucine and lysine) are glucogenic and can thus generate the carbon backbones required for gluconeogenesis. Thus, the correct option is a.
determine the budget for tge fitness event.consider the attendance (should tou ask for registration fee.give shirts etc)
A student obtained an unknown metal sample that weighed 65.3 g and at a temperature of 99.8oC, he placed it in a calorimeter containing 43.7 g of water at 25.7oC. At equilibrium the temperature of the water and metal was 34.5oC. Knowing the specific heat of the water to be 4.18 J/goC, what is the specific heat of the metal
Answer:
0.377 J/gºC
Explanation:
From the question given above, the following data were obtained:
Mass of metal (Mₘ) = 65.3 g
Initial temperature of metal (Tₘ) = 99.8 °C
Mass of water (Mᵥᵥ) = 43.7 g
Initial temperature of water (Tᵥᵥ) = 25.7 °C
Equilibrium temperature (Tₑ) = 34.5 °C
Specific heat capacity of water (Cᵥᵥ) = 4.18 J/gºC
Specific heat capacity of metal (Cₘ) =?
The specific heat capacity of metal can be obtained as illustrated below:
Heat lost by metal = heat gained by water.
MₘCₘ(Tₘ – Tₑ) = MᵥᵥCᵥᵥ(Tₑ – Cᵥᵥ)
65.3 × Cₘ (99.8 – 34.5) = 43.7 × 4.18 (34.5 – 25.7)
65.3Cₘ × 65.3 = 182.666 × 8.8
4264.09Cₘ = 1607.4608
Divide both side by 4264.09
Cₘ = 1607.4608 / 4264.09
Cₘ = 0.377 J/gºC
Therefore the specific heat capacity of the metal is 0.377 J/gºC
The titration of a weak acid with a strong base is a common exercise in chemistry labs. We have looked at all of the individual types of calculations needed to determine the pH at any point of a titration. Consider the titration of 0.100 L of 0.300 M acetic acid with 2.00 M NaOH. What type of calculation will we be performing at the following points of the titration curve
Answer:
1. Weak acid calculation
2. Strong base calculation
3. Strong base calculation
4. Strong base calculation
Explanation:
1. Zero equivalents of base added
2. 0.15 equivalents of base added
3. One equivalent of base added
4. 1.75 equivalents of base added
The equivalents of acetic acid are:
0.100L * (0.300mol/L) = 0.0300 moles of acetic acid = 0.0300Eq.
1. With Zero equivalents of base added you will calculate pH using weak acid calculation because you have only acetic acid (Weak acid) in the solution.
2. When 0.15 equivalents of base are added all the acid reacted and 0.15-0.03 = 0.12 equivalents of Strong base are in excess. With these equivalents and the volume we can find pH using strong base calculation.
3 and 4. As with 0.15 eq. added the 1 eq. and 1.75 eq. produce an excess of strong base and the pH must be calculated by using strong base calculation
The main importance of the titration curve is that it is used show how the pH of the solution changes as a titrant is added to the solution.
What is a titration curve?A titration curve is a plot of pH of the system against the volume of titrant added. The question is incomplete but I will try to explain what a titration curve is.
The main importance of the titration curve is that it is used show how the pH of the solution changes as a titrant is added to the solution.
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Select the missing words to complete the definition of buffer capacity. Buffer capacity is the _____________ of acid or base a buffer can handle before pushing the _____________ outside of the buffer range.
Answer:
amount, pH value.
Explanation:
The buffer range is the pH range in which the buffer performs optimally, i.e., neutralizes even when a strong acid or base is introduced to it and resists any major change in its pH value.
The buffer capacity is the amount of acid or base that can be added before the pH of the buffer solution changes significantly.
Thus, the final statement becomes,
Buffer capacity is the amount of acid or base a buffer can handle before pushing the pH value outside of the buffer range.
Answer:
Amount
pH value
Buffer capacity is the amount of acid or base a buffer can handle before pushing the pH outside of the buffer range.
A buffer however consists of a weak acid and its conjugate base.Its major advantage is the ability to resist changes in pH when an acid or a base is added to the solution.
The human blood is also an example of a buffer solution as it is able to resist changes in pH when we eat or drink certain types of food.
An example of a buffer include acetic acid (HC₂H₃O₂) which is a weak acid and sodium acetate (NaC₂H₃O₂) which is a salt derived from that acid).
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Which gas has the greatest kinetic energy at STP?
H2, Ne, N2 or none
Answer:
none All have the same kinetic energy
Explanation:
Select the statement that best answers the following question What effect does the anion of an ionic compound have on the appearance of the solution?
a. The anion affects the intensity of the color more than the color of the solution.
b. The anion affects the color of the solution more than the intensity of the color.
c. The anion does not affect the color or color intensity of the solution.
d. The anion only affects the intensity of the color in a solution.
Answer:
b. The anion affects the color of the solution more than the intensity of the color.
Explanation:
An ionic compound is one that is made up of ions held together by electrostatic forces. The ions are made up of positively charged ions known as cations and negatively charged ions known as anions. In compounds with a high ionic attribute, anions produce colorless compounds. But compounds that have less ionic attributes produce deeper colors like black and red. When in solutions, ionic compounds take on color and this is because of the anion that absorbs infrared light energy.
discuss the benefits of observing good safety measures in relation to increase in productivity within a pharmaceutical laboratory?
Answer:
Pharmaceutical laboratory helps in devloping and conducting research, vaccines. Various kinds of drugs and chemical substances used and are produced at a Pharmaceutical laboratory.
The pharmaceutical laboratories performs with various hazardous substances that results in exposure to various chemicals, biological substances and radiation. To avoid any injury or infection labs need to maintain all safety measures.
Spillage and relaseing chemical substances can be lethal during transportaions by safety measures for heling in for manufacturing of such therapeutic agents spillage and avoid wastage.
Maintaining good safety standards in the pharmaceuticals laboratory will help promote the health of technicians and workers which in turn will increase productivity and attain positive outcomes.
You are stowing items and come across an aerosol bottle of hairspray. What should you do? Please choose all that apply
Answer:stow the hairspray
Explanation:
On the basis of your knowledge of the reaction of halogens with alkanes, decide which product you would not expect to be formed in even small quantities in the bromination of ethane?
A) BrCH2CH2Br
B) CH3CH2CH2Br
C) CH3CHBr2
D) CH3CH2CH2CH3
E) BrCH2CH2CH2CH2Br
Answer:
On the basis of your knowledge of the reaction of halogens with alkanes, decide which product you would not expect to be formed in even small quantities in the bromination of ethane?
A) BrCH2CH2Br
B) CH3CH2CH2Br
C) CH3CHBr2
D) CH3CH2CH2CH3
E) BrCH2CH2CH2CH2Br
Explanation:
The reaction of ethane with bromine in presence of UV light forms mono substituted ethane at all primary and secondary carbons.
This is an example of free radical substitution.
The structure of ethane and its bromination is shown below:
Among the given options that which is not possible to form is option B) that is CH3CH2CH2Br(propyl bromide).
Remaining all other products are possisble to form on free radical substitution of ethane.
An acetic acid buffer containing 0.50 M acetic acid (CH3COOH) and 0.50 M sodium acetate (CH3COONa) has a pH of 4.74. What will the pH be after 0.0020 mol of HCl has been added to 100.0 mL of the buffer
Answer:
pH = 4.71
Explanation:
We can find the pH of a buffer (Mixture of weak acid: CH3COOH, and its conjugate base: CH3COONa) using H-H equation:
pH = pKa + log [CH3COONa] / [CH3COOH]
Where pH is the pH of the buffere = 4.74, pKa the pka of the buffer and [] could be taken as the moles of each reactant.
As initially [CH3COONa] = [CH3COOH], [CH3COONa] / [CH3COOH] = 1:
pH = pKa + log 1
4.74 = pKa
To solve this question we need to find the initial moles of each species, The CH3COONa reacts with HCl to produce CH3COOH. That means the moles of CH3COOH after the reaction are: Initial CH3COOH + Moles HCl
Moles CH3COONa: Initial CH3COONa - Moles HCl.
Moles CH3COOH:
0.100L * (0.50mol / L) = 0.050 moles CH3COOH + 0.0020 moles HCl =
0.052 moles CH3COOH
Moles CH3COONa:
0.100L * (0.50mol / L) = 0.050 moles CH3COONa - 0.0020 moles HCl =
0.048 moles CH3COONa
Using H-H equation:
pH = 4.74 + log [0.048 moles] / [0.052 moles]
pH = 4.71The pH be after 0.0020 mol of HCl has been added to 100.0 mL of the buffer is 4.71.
What is buffer solution?Buffer solution is a mixture of weak acid and its conjugate base or vice versa.
We can calculate the pH of buffer solution by using Henderson - Hasselbalch Equation:
pH = pKa + log[CH₃COONa] / [CH₃COOH]
Initially concentration of CH₃COONa is equal to the concentration of CH₃COOH and equal becomes:
4.74 = pKa + log(1)
pKa = 4.74
Given moles of added HCl moles = 0.002 mole
Given molarity of each CH₃COOH & CH₃COONa = 0.50M
Given Volume = 100mL
We can calculate the moles by using the formula:
n = M × V
Moles of CH₃COOH & CH₃COONa = 0.100 × 0.50 = 0.050 moles
Moles of CH₃COOH = 0.050moles CH₃COOH + 0.0020moles HCl =
0.052moles CH₃COOH
Moles of CH₃COONa = 0.050moles CH3COONa - 0.0020moles HCl =
0.048moles CH₃COONa
Now, resultant pH will be:
pH = 4.74 + log [0.048 moles] / [0.052 moles]
pH = 4.71
Hence, pH of resultant solution is 4.71.
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The table shows the nature of reactants and products formed in a certain type of chemical reaction.
Nature of Reactants and Products
Reactants
Metal + lonic compound
Products
Metal + lonic compound
Which of the following is true about the type of chemical reaction?
it is a single replacement reaction, and the anions in the two inic compounds are different.
It is a single replacement reaction, and the cations in the two ionic compounds are different.
It is a double replacement reaction, and the anions in the two ionic compounds are different.
It is a double replacement reaction, and the cations in the two ionic compounds are different.
Answer: It is true about the type of reaction that it is a single replacement reaction, and the cations in the two ionic compounds are different.
Explanation:
When one element in a compound is replaced by another element in a chemical reaction then it is called a single replacement reaction.
For example, [tex]K + NaCl \rightarrow KCl + Na[/tex]
Here, potassium metal is replacing the sodium metal in the sodium chloride compound.
As metals become cation by losing an electron in a chemical reaction.
Thus, we can conclude that it is true about the type of reaction that it is a single replacement reaction, and the cations in the two ionic compounds are different.
Answer: Its A
Explanation:
a single replacement reactions, and the ANIONS in the two ionic compounds are different
The following statements either define or are closely related to the terms periodic law, period, or group. Match the terms to the appropriate statements.1. This is a vertical arrangement of elements in the periodic table. 2. This is a horizontal arrangement of elements in the periodic table. 3. The properties of the elements repeat in a regular way as the atomic numbers increase. 4. Element 19 begins this arrangement in the periodic table 5. The chemical properties of elements 12, 20, and 38 demonstrate this principle.
Answer:
Please find the complete solution in attached file.
Explanation:
Periodic law is the the properties of the elements that repeat in a regular way as the atomic numbers increase.
What is periodic table?Periodic chart organized collection of all chemical elements arranged roughly according to increasing atomic weight. The periodic recurrence of several features in the elements was originally identified by Dmitry I. Mendeleyev in 1869.
1. This is a vertical arrangement of elements in the periodic table group
2. This is a horizontal arrangement of elements in the periodic table period
3. The properties of the elements repeat in a regular way as the atomic numbers increase periodic law
4. Element 19 begins this arrangement in the periodic table period
5. The chemical properties of elements 12, 20, and 38 demonstrate this principle. periodic law
Therefore, periodic law is the the properties of the elements that repeat in a regular way as the atomic numbers increase.
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54
Penny bought a club moss plant for her water garden. She needs to know how tall the plant will grow so she know
how much space it will need.
How tall will the plant likely grow?
O less than 5 centimeters because it is a seedless vascular plant
less than 5 centimeters because it is a nonvascular plant
O more than 5 centimeters because it is a seedless vascular plant
O more than 5 centimeters because it is a nonvascular plant
Answer:
less than 5 centimeters because it is a nonvascular plant
Explanation:
Mosses are a group of plants under the division Bryophyta. They are said to be the most primitive plant life in existence as they lack true roots, stems and leaves. They also lack vascular system, hence, they are regarded as non-vascular plants. They usually grow in very small sizes (about 0.2 - 10cm).
According to this question, Penny bought a club moss plant for her water garden and needs to know how tall the plant will grow so she know how much space it will need. Since it is a miss plant that lacks vascular tissues i.e. nonvascular, it will likely grow less than 5 centimeters in height.
Answer:
d
Explanation:
Excluding any secondary chemical reactions,
which would be more effective as an antifreeze; a
solution containing
Select one:
25m CH3OH
the combination of 25m CH3OH and 25m
KCI.
O 25m KCI.
O
none of these
Answer:
Excluding any secondary chemical reactions,
which would be more effective as an antifreeze; a
solution containing
Select one:
25m CH3OH
the combination of 25m CH3OH and 25m
KCI.
25m KCI.
Explanation:
Antifreeze is the one that reduces the freezing point of a solvent further and will not allow the solvent to freeze.
Among the given options, the correct option is:
25 m CH3OH and 25m KCl.
Since, KOH is a strong electrolyte and dissociates into two ions.
So, the freezing point of solvent decreases further.
The enthalpy of Sodium is 235 calories. The enthalpy Chlorine is 435 calories. The enthalpy of Sodium chloride 670 joules, what is the change in enthalpy for this reaction?
Answer:
ΔH = -2446J
Explanation:
Based on the reaction:
2 Na(s) + Cl2(g) → 2NaCl
We can find the enthalpy of this reaction using Hess's law:
The enthalpy of a reaction is equal to the sum of the enthalpy of products times their reaction quotient subtracting the enthalpy of reactants times their reaction quotient. For the reaction of the problem:
ΔH = 2ΔH(NaCl) - [2ΔH(Na) + ΔHCl2)]
ΔH(NaCl) = 670J
ΔH(Na) = 235cal * (4.184J/1cal) = 983J
ΔHCl2 = 435cal * (4.184J/1cal) = 1820J
ΔH = 2*670J - [2*983J + 1820J]
ΔH = 1340J - [3786J]
ΔH = -2446JAnswer:
the heat content of a system at constant pressure
Explanation:
The element antimony has two stable isotopes, antimony-121 with a mass of 120.90 amu and antimony-123 with a mass of 122.90 amu. From the atomic weight of Sb = 121.76 one can conclude that: ________
antimony-123 has the highest percent natural abundance
most antimony atoms have a mass of 121.76 amu
antimony-121 has the highest percent natural abundance
both isotopes have the same percent natural abundance
Answer:
antimony-121 has the highest percent natural abundance
Explanation:
percent natural abundance;
121.76 = 120.90 x + 122.90 (1 - x)
121.76 = 120.90 x + 122.90 - 122.90x
121.76 = -2x + 122.90
121.76 - 122.90 = -2x
x= 121.76 - 122.90/ -2
x= 0.57
Where x and 1 - x refers to the relative abundance of each of the isotopes
Percent natural abundance of antimony-121 = 57 %
Percent natural abundance of antimony-123 = (1 - 0.57) = 43%
Let us remember that isotopy refers to a phenomenon in which atoms of the same element have the same atomic number but different mass numbers. This results from differences in the number of neutrons in atoms of the same element.
We can clearly see that antimony-121 has the highest percent natural abundance.
Glass tubes of the following diameters are arranged in a water trough. Rank the following glass tubes in decreasing order of their capillary rise.
Rank from highest to lowest capillary rise. To rank items as equivalent, overlap them.
1.25 mm, 1 mm, 0.75 mm, 0.25 mm, 0.50 mm
Answer:
0.25 mm> 0.50 mm > 0.75 mm> 1mm> 1.25 mm
Explanation:
Capillary movement involves the movement of liquid up through a capillary tube.
Looking at the question, we can see all the various diameters of the capillary tube are involved.
Note that, that the narrower the diameter of the capillary tube, the better the capillary action of the liquid (the liquid rises more now than then).
Where do reactions in a solid
generally take place?
A. All throughout the solid
B. At the center of the solid.
C. Only on opposite sides of the solid
due to repelling forces.
D. On the surface of the solid.
Answer:
A
Explanation:
because solid stick together like magnetic and can feel every vibration
Answer:D
Explanation: on the surface of a solid
How many grams of O2 are needed to react with 8.15 g of C2H2?
Answer:
25.08 grams of O₂ are needed to react with 8.15 g of C₂H₂.
Explanation:
The balanced reaction is:
2 C₂H₂ + 5 O₂ → 4 CO₂ + 2 H₂O
By reaction stoichiometry, the following amounts of moles of each compound participate in the reaction:
C₂H₂: 2 molesO₂: 5 molesCO₂: 4 molesH₂O: 2 molesThe molar mass of each compound is:
C₂H₂: 26 g/moleO₂: 32 g/moleCO₂: 44 g/moleH₂O: 18 g/moleThen, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:
C₂H₂: 2 moles* 26 g/mole= 52 gO₂: 5 moles* 32 g/mole= 160 gCO₂: 4 moles* 44 g/mole= 176 gH₂O: 2 moles* 18 g/mole= 36 gThen you can apply the following rule of three: if by stoichiometry 52 grams of C₂H₂ react with 160 grams of O₂, 8.15 grams of C₂H₂ react with how much mass of O₂?
[tex]mass of O_{2} =\frac{8.15 grams of C_{2} H_{2}*160 grams of O_{2} }{52 grams of C_{2} H_{2}}[/tex]
mass of O₂= 25.08 grams
25.08 grams of O₂ are needed to react with 8.15 g of C₂H₂.
Suppose an enzyme and its substrate obey the lock and key model of enzyme catalysis. Which of the following would be true of the enzyme?
a. only one substrate could be converted to product by the enzyme
b. the active site of the enzyme must be rigid
c. the entire enzyme must be rigid
d. the active site of the enzyme must be flexible
e. the enzyme could bind different substrates if the substrates shared a common motif somewhere in their structures
Answer:
only one substrate could be converted to product by the enzyme
Explanation:
If an enzyme obeys the lock and key model, it then follows that the design of the enzyme is unique to a particular substrate.
Just as only the correct key can effectively fit into a lock, only the appropriate substrate whose design matches that of the enzyme can fit into the enzyme.
Owing to the lock and key model of enzyme activity, only one enzyme could interact with a substrate to yield particular product.
A product of homolytic fission can never be
a - charged
b - nucleophile
c- both
d-none of these
Answer:
both
Explanation:
A homolytic fission is said to have occurred when the breakage of a bond between two atoms leaves each of the bonding atoms with equal number of electrons. Homolytic fission often results in the creation of radicals.
Since homolytic fission yields two species with equal number of electrons(usually odd number of electrons), the products of such process can not be charged. They can not be nucleophiles because nucleophiles need to possess two electrons which can be shared with another chemical specie.
