Answer:
a. The student performed the splint test incorrectly. He should of observed a popping sound when the splint was placed in the test tube.
Explanation:
It is given that a student performed an experiment where he dropped a nickel metal in to HCl solution. He observed the reaction and performed a splint test in the test tube that is filled with a gas which is formed while Nickle is dropped into the solution of HCl.
But the experiment that the student performed was incorrect. He must have observed the popping sound when the splint was placed in the test tube.
When the splint was added to the gas splint flared up. The hydrogen gas pops out when exposed to the flame.
[tex]$Ni + HCl(aq) = NiCl + H_2$[/tex]
Thus the correct option is (a).
Which of the following was NOT explained by Dalton's atomic theory?
A. the Law of Multiple Proportions
B. the difference between elements and compounds
C.?the difference between isotopes of an element
D. the Law of Conservation of Mass
Answer:
A. The law of Multiple Proportion
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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Excited sodium atoms may emit radiation having a wavelength of 589nm. a) What is the wavelength in meters
Answer: When excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
Explanation:
Given: Wavelength = 589 nm
It is known that,
[tex]1 nm = 10^{-9} m[/tex]
Hence, 589 nm is converted into meters as follows.
[tex]589 nm = 589 nm \times \frac{10^{-9}m}{1 nm}\\= 589 \times 10^{-9} m[/tex]
Thus, we can conclude that when excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
Using the balanced equation for the combustion of ethane: 2C2H6 + 7O2 → 4CO2 + 6H2O, how many moles of O2 needed to produce 12 moles of H2O?
Answer:
14 moles of oxygen needed to produce 12 moles of H2O.
Explanation:
We are given that balance eqaution
[tex]2C_2H_6+7O_2\rightarrow 4CO_2+6H_2O[/tex]
We have to find number of moles of O2 needed to produce 12 moles of H2O.
From given equation
We can see that
6 moles of H2O produced by Oxygen =7 moles
1 mole of H2O produced by Oxygen=[tex]\frac{7}{6}[/tex]moles
12 moles of H2O produced by Oxygen=[tex]\frac{7}{6}\times 12[/tex]moles
12 moles of H2O produced by Oxygen=[tex]7\times 2[/tex]moles
12 moles of H2O produced by Oxygen=14 moles
Hence, 14 moles of oxygen needed to produce 12 moles of H2O.
The amount of oxygen required for the combustion of ethane to produce 12 moles of water is 14 moles.
How are the moles produced in reaction calculated?The moles of oxygen produced in the reaction can be given from the stoichiometric law of the balanced chemical equation.
The balanced chemical equation for the combustion of ethane is:
[tex]\rm 2\;C_2H_6\;+\;7\;O_2\;\rightarrow\;4\;CO_2\;+\;6\;H_2O[/tex]
The 6 moles of water are produced from 7 moles of oxygen. The moles of oxygen required to produce 12 moles of water are:
[tex]\rm 6\;mol\;H_2O=7\;mol\;Oxygen\\12\;mol\;H_2O=\dfrac{7}{6}\;\times\;12\;mol\;O_2\\ 12\;mol\;H_2O=14\;mol\;O_2[/tex]
The moles of oxygen required to produce 12 moles of water are 14 moles.
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Explain the various factors that impact the solubility of substances in water.
(At least 4 sentences) :)
The various factors that impact the solubility of substances in water are - nature of solute and solvent, temperature, pressure and pH.
The solubility of substances in water is influenced by several factors:
Nature of the solute and solvent: The chemical properties of both the solute and the solvent play a significant role. Substances with similar polarities and intermolecular forces tend to dissolve more readily in water. Polar solutes, such as salts and sugars, dissolve well in polar solvents like water, whereas nonpolar solutes, like oils and fats, have low solubility in water.Temperature: In general, an increase in temperature enhances the solubility of solid solutes in water, as it provides more energy for the solute particles to overcome intermolecular forces and mix with the solvent. However, the effect of temperature on solubility can vary depending on the specific solute. For some solutes, such as gases, solubility decreases with increasing temperature.Pressure (for gases): The solubility of gases in water is influenced by pressure. According to Henry's law, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. Therefore, an increase in pressure generally leads to an increase in gas solubility in water.pH: The pH of the solution can impact the solubility of certain substances. For example, the solubility of acidic or basic compounds may change with varying pH levels.Learn more about Solubility, here:
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What effect would a decrease in volume have on pressure, assuming that temperature (T) and moles of gas (n) are kept constant
Answer:
Pressure increases
Explanation:
Boyle's law states that; '' the volume of a given mass of ideal gas is inversely proportional to its pressure at constant temperature.
Hence, when the volume of a given mass of ideal gas is decreased, the molecules of the gas come closer together so they collide with each other and the walls of the container more frequently.
This implies that the pressure of the gas increases as volume decreases in accordance with Boyle's law.
According to the following pKa values listed for a set of acids, which would lead to the strongest conjugate base?
a. -2.
b. 1.
c. 7.
d. 25.
e. 50.
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.
The tools shown in the diagram are used for gardening Each tool is made up
of two levers that are attached to each other. The handles are the input arms,
and the cutting blades are the output armo
Hand shears
Lopper
Which tool has a greater mechanical advantage, and why?
A. The lopper, because the input work is the same as the output work
B. The hand shears, because their shorter handles transfer force
more quickly to the cutting blade
C. The hand shears, because you can apply less total force to the
handles with one hand
D. The lopper, because its longer handles can produce more output
force with less input force
Answer:
D
Explanation:
The longer handles distribute the force across a longer distance.
A sample of oxygen gas is compressed from 30.6 L to 1.8 L at constant temperature pressure of 1.8 atm. Calculate the amount of energy in joules when the system releases 1.5 KJ of heat?
Answer:
the change in the internal energy of the system is 3,752.67 J
Explanation:
Given;
initial volume of the gas, V₁ = 30.6 L
final volume of the gas, V₂ = 1.8 L
constant pressure of the gas, P = 1.8 atm
Energy released by the system, Q = 1.5 kJ = 1,500 J
Apply pressure-volume work equation, to determine the work done on the gas;
w = -PΔV
w = -P(V₂ - V₁)
w = - 1.8 atm(1.8 L - 30.6 L)
w = 51.84 L.atm
w = 51.84 L.atm x 101.325 J/L.atm
w = 5,252.67 J
The change in the internal energy of the system is calculated as;
ΔU = Q + w
Since the heat is given out, Q = - 1,500 J
ΔU = -1,500 J + 5,252.67 J
ΔU = 3,752.67 J
Therefore, the change in the internal energy of the system is 3,752.67 J
In the titration of 82.0 mL of 0.400 M HCOOH with 0.150 M LiOH, how many mL of LiOH are required to reach the equivalence point
Answer:
218.7 mL
Explanation:
The reaction that takes place is:
HCOOH + LiOH → LiCOOH + H₂OFirst we calculate how many HCOOH moles reacted, using the given volume and concentration:
82.0 mL * 0.400 M = 32.8 mmol HCOOHAs 1 HCOOH mol reacts with 1 LiOH mol, 32.8 mmoles of LiOH are needed to react with 32.8 mmoles of HCOOH.
Finally we calculate how many mL of a 0.150 M solution would contain 32.8 mmoles:
32.8 mmol / 0.150 M = 218.7 mLg Calculate the number of grams of aluminum that is produced in 1.00 h by the electrolysis of molten AlCl3 if the electrical current is 10.0A.
Answer:
3.36 grams Al°(s)
Explanation:
Given AlCl₃(s), determine the mass (grams) of Al°(s) produced from electrolysis of Aluminum Chloride at 10.0 amps for 1.00 hour.
AlCl₃(s) + 378.3°F (=192.4°C) => Al⁺³(l) + 3Cl⁻(l)
formula wt. Al° = 27g/mol
Faraday Constant (F°) = 96,500 amp·sec
? grams Al°(s) = 10.0amps x (1 mole e⁻/96,500amp-sec) x (1 mole Al°(s)/3 mole e⁻) x (27g Al°(s)/1 mole Al°(s)) x 3,600 sec = 3.36 grams Al°(s)
The 3.36 grams of aluminum are produced in 1 hour by the electrolysis of molten AlCl₃ when 10A current is passed.
What is electrolysis?Electrolysis is a process that uses an electrical current to break chemical compounds. The electric current is passed through the substance to bring the chemical change by gain or loss of electrons.
The electrolysis of the aluminum chloride in the molten state is represented as:
AlCl₃ → Al³⁺ + 3Cl⁻
At cathode: Al³⁺ + 3e⁻ → Al (s)
Given, the current. I = 10 A and t = 1 hr = 3600 s
We know that the current is calculated from the equation: I = q/t
q = I× t
q = (10A) × (3600s)
q = 36 × 10³ C
We know, 96500 C of the charge has electrons = 1 mol
36 × 10³ C of the charge has electrons = 0.373 mol
3 moles of electrons required to produce aluminum = 1 mol
0.373 mol of electrons will produce aluminum = 0.373/3 = 0.124 mol
We know that, the mass of one mole of Al = 27g
The mass of 0.124 mol of Al = 27 × 0.124 = 3.36 g
Therefore, the aluminum produced in 1 hour by the electrolysis of molten AlCl₃ is equal to 3.36 grams.
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jawbone root nerve cementum blood vessel gum crown Fill in the blanks. 1. The front four teeth on each jaw are called 2. Each tooth is attached to the jawbone with the help of 3. A healthy tooth is held firmly in the jawbone by the 4. Teeth can get spoilt if they are not kept 5. Germs in the mouth feed on sugar and make
Answer:
shduxhheufufffhduduf
What is the mass number of an ion with 106 electrons, 157 neutrons, and a +1 charge?
Answer:
264 g/mol
Explanation:
#electrons equal #protons = 106
Plus 1 charge => m protons = 106 + 1 = 107
Mass number: 107 + 157 = 264 g/mol
What would be the specific mathematical effect on the reaction rate if you carried out the sodium iodide-in-acetone reactions on the alkyl halides using an iodide solution half as concentrated? ("Slower" or "faster" is not specific enough.)
Answer:
Slower
Explanation:
The reaction between alkyl halides and sodium iodide-in-acetone is an SN2 reaction. The rate of reaction depends on the concentration of the alkyl halide as well as the concentration of the sodium iodide. It is a bimolecular reaction.
This means that if the concentration of any of the reactants is halved, the rate of reaction decreases accordingly.
Therefore, if the iodide solution is half as concentrated, the reaction is observed to be slower in accordance with the rate law;
Rate = k[alkyl halide] [iodide]
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).
Cathode rays are beams of?
electrons
protons
anions
neutrons
Answer:
Electrons
Explanation:
Electrons are produced when light with enough energy is directed onto the cathode where electrons are ejected as beam towards the screen.
How many moles of
H
C
l
are in
44.1
mL
of a
1.26
M
H
C
l
solution?
Answer: There are 0.0556 moles present in 44.1 mL of a 1.26 M HCl solution.
Explanation:
Given: Volume = 44.1 mL (1 mL = 0.001 L) = 0.0441 L
Molarity = 1.26 M
Molarity is the number of moles of a substance present in liter of a solution.
Therefore, moles of HCl are calculated as follows.
[tex]Moles = \frac{moles}{Volume (in L)}\\1.26 M = \frac{moles}{0.0441 L}\\moles = 0.0556 mol[/tex]
Thus, we can conclude that there are 0.0556 moles present in 44.1 mL of a 1.26 M HCl solution.
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Which statement describes an electron?
EEEE
It has a positive charge and is located in the nucleus.
O It has a positive charge and is located in orbitals around the nucleus.
It has a negative charge and is located in the nucleus.
O It has a negative charge and is located in orbitals around the nucleus.
Answer:
It has a negative charge and is located in orbitals around the nucleus
Explanation:
The statement describes an electron is " It has a negative charge and is located in orbitals around the nucleus."
What is electron?The electron would be a subatomic particle with a negatively one elementary charge electric charge.
What is nucleus?Protons, that have a positive charge, as well as neutrons, which have no electrical charge, make up the nucleus. Quarks were subatomic particles that make up protons but also neutrons.
Electrons were present surrounding the atom's nucleus, in contrast to protons as well as neutrons, that are contained within the nucleus at its core. Negative electrons were drawn to the positive nucleus since the electric charges of opposite polarity attract one another.
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determine the budget for tge fitness event.consider the attendance (should tou ask for registration fee.give shirts etc)
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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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:
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.
In a sample of oxygen gas at room temperature, the average kinetic energy of all the balls stays constant. Which postulate of kinetic molecular theory best explains how this is possible?
A. Attractive forces between gas particles are negligible because the particles of an ideal gas are moving so quickly.
B. Collisions between gas particles are elastic; there is no net gain or loss of kinetic energy.
C. Gases consist of a large number of small particles, with a lot of space between the particles.
D. Gas particles are in constant, random motion, and higher kinetic energy means faster movement.
Answer:
Collisions between gas particles are elastic; there is no net gain or loss of kinetic energy.
Explanation:
When a gas is paced in a container, the molecules of the gas have little or no intermolecular interaction between them. There is a lot of space between the molecules of the gas.
The gas molecules move at very high speed and collide with each other and with the walls of container.
The collision of these particles with each other is perfectly elastic hence the kinetic energy of the colliding gas particles do not change.
g The theoretical yield of a certain reaction is 123 g of Al2O3. If the actual yield when the experiment is performed is 0.209 mol Al2O3, what is the percent yield
Answer:
Percent yield = 17.3%
Explanation:
The percent yield is defined as 100 times the ratio between actual yield in grams and theoretical yield in grams (123g).
Percent Yield = Actual Yield / Theoretical yield (123g) * 100
To find actual yield we need to convert the 0.209moles to grams:
Actual yield -Molar mass Al2O3: 101.96g/mol-
0.209mol * (101.96g/mol) = 21.3g
Percent yield = 21.3g / 123g * 100
Percent yield = 17.3%
can anybody pls help me with chemistry how to balance an equation of class 7 ??? pls
really I don't like chemistry..
I need only the step(s)..
Answer:
[tex] This\:may\: help[/tex]
Answer:
(1) Write down the chemical reaction in the form of word equation,keeping reactants on left hand side and products on right hand side.
(2) Write symbol and formula of all reactants and products in word equation. (3) Balance the equation by multiplying the symbols and formula by smallest possible figures.
All --- is a good conductor of heat
A student observes a chemical
reaction where two liquids are mixed together. After the liquids are mixed the beaker feels cold to touch. This reactions is an
example of a
reaction.
Synthesis
Combustion
Exothermic
Endothermic
Answer:
Endothermic
Explanation:
Endothermic reaction is one in which the enthalpy increases. What this implies is that, it is a closed system which absorbs heat from its surroundings and thus after reaction become cooler than prior to the reaction.
In this case, the mixture of the two liquids feel colder to touch. Thus, it is an endothermic reaction from the definition earlier given.
1) Write a balanced equation to show the reaction of gaseous ethane with gaseous oxygen to form carbon monoxide gas and water vapor.
Answer:
C₂H₆(g) + 2.5 O₂(g) ⇒ 2 CO(g) + 3 H₂O(g)
Explanation:
Let's consider the unbalanced equation in which gaseous ethane reacts with gaseous oxygen to form carbon monoxide gas and water vapor. This is an incomplete combustion reaction.
C₂H₆(g) + O₂(g) ⇒ CO(g) + H₂O(g)
We will balance it using the trial and error method.
First, we will balance C atoms by multiplying CO by 2 and H atoms by multiplying H₂O by 3.
C₂H₆(g) + O₂(g) ⇒ 2 CO(g) + 3 H₂O(g)
Then, we get the balanced equation by multiplying O₂ by 2.5.
C₂H₆(g) + 2.5 O₂(g) ⇒ 2 CO(g) + 3 H₂O(g)
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
