Answer:
The initial temperature of the brass sample is 90.1°C
Note: The question is incomplete. A similar but complete question is given below :
A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g−1°C−1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample. Be sure your answer is rounded to 2 significant digits.
Explanation:
Assuming that the calorimeter is an isolated system and that no heat is lost from the calorimeter. The total heat in the system is the sum of the heat content of the brass and that of water
Total heat lost by the brass = heat gained by the water
The quantity of heat lost or gained, Q = mcΔT
Where m = mass of the substance, c = specific heat capacity of substance, ΔT = temperature change
Heat gained by water is positive while heat lost by brass is negative
mass of brass = 52.9 g, specific heat capacity of brass = 0.375·J·g−1°C−1, ΔT = (18.4 - t °C; where t is the initial temperature), mass of water = 100.0 g, specific heat capacity of water = 4.186 J/g°C, ΔT = = 18.4 - 15.0 = 3.4 °C
Heat lost by brass z= - [ 52.9 × 0.375 × (18.4 - t)] = -365.01 + 19.8375t
Heat gained by water = 100 × 4.186 × 3.4 = 1423.24
Equating heat lost by brass to heat gained by water
-365.01 + 19.8375t = 1423.24
19.8375t = 1423.24 + 365.01
19.8375t = 1788.25
t = 90.1° C
Therefore, the initial temperature of the brass sample is 90.1°C
How can beta particles be dangerous to living cells?
A. They move fast and penetrate the skin.
B. They are very high in energy and can travel through most
materials.
C. They move slowly but are very large.
D. They are very low in energy but remain in the body for a long time.
Which type of organic compound is shown below?
A. Carboxylic acid
B. Ester
C. Amine
D. Alcohol
Answer:
I think its A maybe am not sure
The number of organic compounds that have been reported in 2019 is more than 10 million. This is due to carbon's ability to bond to other carbon molecules, called
electron affinity.
ionic bonding.
catenation.
electronegativity.
Answer:
catenation
Explanation:
Carbon atoms have four electrons to share in bonding environments to get to the ideal octet. To do this, it bonds with other carbon molecules, called catenation. Catenation is the ability of an atom to bond and share electrons with other atoms of its kind.
A sample of an ideal gas is slowly compressed to one-half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample
Answer:
See explanation
Explanation:
The average speed of the molecules of a gas depends on the temperature of the gas and its molar mass and not on the volume of the gas.
The average velocity of a gas is given by; vrms=√3RTM
R= gas constant
T= Absolute temperature
M= molar mass of the gas
Where the temperature of the gas is held constant, the average velocity of gas molecules depends on the molar mass of the gas. Hence, if a sample of gas is slowly compressed to one-half of its original volume with no change in temperature, the average speed of the molecules in the sample of gas remains the same.
Buffer solutions that maintain certain levels of pH or acidity are widely used in biochemical experiments. One common buffer system uses sodium dihydrogenphosphate and sodium monohydrogenphosphate. What are the formulas of these two compounds
Answer:
Sodium dihydrogenphosphate = NaH₂PO₄
Sodium monohydrogenphosphate = Na₂HPO₄
Explanation:
A buffer solution is a solution is a solution that resists changes to its oH when a little quantity of strong acid or strong base is added to it.
They are solutions of weak acids or weak bases and their salts known as conjugate base or conjugate acids respectively for the weak acids and weak bases.
For example, a solution of the weak acid ethanoic acid and its salt or conjugate base, sodium ethanoate serves as a buffer solution.
In biochemical experiments, where the pH of the reaction medium is kept as constant and as close as possible to that of the internal environment, buffer solutions are widely used. One of the commonly used buffers is the phosphate buffer. The phosphate buffer consists of the acid salts sodium dihydrogenphosphate and sodium monohydrogenphosphate. Sodium dihydrogenphosphate serves as the weak acid while sodium monohydrogenphosphate serves as the conjugate base.
The formulas of these two compounds are given below:
Sodium dihydrogenphosphate = NaH₂PO₄
Sodium monohydrogenphosphate = Na₂HPO₄
Which one of the following compounds
contains ionic bonds?
a) NI3
B) HF
c) SiO2
d) CaO
Your answer is CaO.I hope that my answer helped you..
A new member of your team is visually impaired. He's having a hard time reading his computer screen. How can you show that you value diversity? a) Suggest the organization may not be a great fit. O b) Tell him to apply for a different job within the organization that does not b) require computer usage. 12 Od Tell him that he might want to schedule an eye exam. c) d) Provide access to technology that can magnify or read what is on the computer screen.
Answer:
C
Explanation:
If he can't read his computer screen. Means his eyes have problem
A new member of your team is visually impaired. He's having a hard time reading his computer screen. value diversity require computer usage. 12 Tell him that he might want to schedule an eye exam. Therefore, option C is correct.
What is value diversity ?Institutions and community members who value diversity do so in order to recognize the advantages of both their differences and commonalities. They make a deliberate effort to forge enduring connections between individuals and organizations with a broad membership.
When people's unique qualities, abilities, interests, and viewpoints are recognized and supported, they develop a stronger sense of self and health and achieve better results in their academic and professional endeavors.
Although diversity and inclusion are related ideas, they are not the same thing. Diversity has to do with representation or how something is put together. The degree to which the contributions, presence, and viewpoints of other groups of individuals are appreciated and incorporated into a setting is referred to as inclusion.
Thus, option C is correct.
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12 grams of carbon is burnt with a certain amount of air containing 36 grams of oxygen. The product contains 24 grams of Co, and 4 grams of CO. Calculate the percentage of excess oxygen.
Answer:
C
Oxygen gas is limiting.
C(s) + O
2
→CO
2
(g)
No. of moles of carbon =
12
36
=3 moles
No. of moles of oxygen =
32
32
=1 moles
So, 2 moles of carbon is left and oxygen will be completed.
So, O
2
is limiting reagent.
Answer:
14.5
Explanation:
not sure how I got it but I hope this helped!
4. A balloon is filled with 3.0 L of helium at 310 K. The balloon is placed in an oven where the
temperature reaches 340 K. What is the new volume of the balloon?
Answer:
3,29L
Explanation:
3.29L = V2
Formula: V1/T1 = V2/T2
--------------------
Given:
V1 = 3.0 L V2 = ?
T1 = 310 K T2 = 340 K
--------------------
Plugin:
(X stands in place of V2 just to make it easier to look at)
[3.0L / 310K = X / 340K]
(3.0L / 310K = 0.01L/K)
0.01L/K = X / 340K
(multiply 340K on both sides, it cancels out on the right)
0.01L/K * 340K = X
(0.01L/K * 340K = 3.29L)
**3.29L = X**
[or]
**3.29L = V2**
In the reaction HCI + NH4OH --> NH4CI+H2O, which compound has an element ratio of 1:4:1?
H2O
NH4Cl
HCI
ΝΗ4ΟΗ
The compound in this reaction which is having the elemental ratio of 1:4:1 is NH₄Cl where nitrogen and chlorine are of one mole each with 4 hydrogens.
What is elemental ratio?Elemental ratio of a compound is the ratio of number of atoms of each elements in that compound. The elemental ratio can be determined from the molecular formula of compounds.
The given reaction is a double displacement reaction. Here, the Cl group is replaced to the ammonia and OH group is replaced to the water. Thus, two species is replaced in the reaction.
In NH₄Cl, there are one nitrogen, 4 hydrogens and one chlorine atom. Therefore, the elemental ratio of the compound is 1:4:1. The elemental ratio of water is 2:1 and HCl is 1:1 and that in NH₄OH is 1:5:1. Hence, option b is correct.
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.formular for Charles' law
Explanation:
Hey there!
Charles law states that the volume of gas is directly proportional to the absolute temperature at constant pressure.
As the fact is, at a constant pressure the volume of fix amount of dry gas is directly proportional to absolute temperature from Charles law.
Since V and T are directly varying directly, we can write the equation using constant "k".
V/T = k
In this case the value of k depends on the pressure of gas, the amount of gas and also unit volume.
V/T = k .........(i)
Let us consider V1 and T1 the Volume and temperature of the ideal gases.
Then the equation is;
V1/T1 =k........(ii)
After this let change the temperature and volume be T2 and V2, respectively.
Then the equation is:
V2/T2 = k.......(iii)
Now; Equating equation (ii) and (iii)…
V1/T1 = V2/T2
So, this the formula. (i.e V1/T1 = V2/T2).
Hope it helps!
How many grams of Br are in 445 g CaBr2 ?
Explanation:
The mass of bromine is 79.904, and since there are two of them in the Calcium Bromide molecule, we'll multiply it by 2 to get 159.808. Dividing that by the full mass of the molecule then multiply it by 100 will give you the answer.
what happened when potassium chloride is added to silver nitrate solutions . there no reaction B two soluble salts are formed C two insoluble salts are formed D. one soluble salts and one insoluble salts are formed.
Answer:
D. One soluble and one insoluble salts are formed
Explanation:
When cyclopentane undergo free-radical substitution with bromine (Br2 /Heat) the product:
a. Bromo cyclopentene
b. Bromo cyclopentane + HBr
c. Bromo cyclopentene + HBr
Explanation:
b. Bromo cyclopentane + HBr
Provide two real world examples of habitats and niches within ecosystems? Explain the interdependence that exists within those ecosystems.
Answer:
An ecosystem encompasses living organisms and the nonliving elements of their environments. Hence, the components of an ecosystem include animals, plants, microorganisms, rocks, soil, minerals, atmosphere, and the surrounding water masses. An ecosystem can be huge, cutting across several nations, or it can be relatively small, such as the body of an animal, which is home to numerous microorganisms.
We can describe ecosystems under two headings – natural ecosystems and unnatural ecosystems. Unnatural ecosystems, which include agricultural and urban areas, are greatly modified and maintained by human activity. Conversely, natural ecosystems are self-sufficient, balanced ecological units, with a high proportion of native biodiversity and minimal human disruption.
The natural ecosystem is broad. It is divided into two major groups – terrestrial and aquatic ecosystems. These are further divided into many other smaller types of ecosystems as outlined in this article.
Explanation:
Hope it helps.. if yes, plz mark me as brainliest
List the following substances in order of decreasing boiling point:
CO2, Ne, CH3OH, KF
The correct order of the substances in order of decreasing boiling point is,
KF , CH30OH , CO2 , Ne
What is boiling point?Boiling point, the temperature at which the force exerted by the surroundings upon a liquid exists equaled by the pressure exerted by the vapor of the liquid; under this situation, the addition of heat affects the transformation of the liquid into its vapor without increasing the temperature.
The main difference between the boiling point and the melting point stands that the melting point is determined as the temperature at which solid and liquid phases exist in equilibrium, whereas the boiling point stands as the temperature at which the vapor pressure of a liquid stands equal to the external pressure.
Hence, The correct order of the substances in order of decreasing boiling point is,
KF , CH30OH , CO2 , Ne
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What is the trend in electropositivity in group 1 elements?
Answer:
Electro positivity increases down the group
Complete the sentences by identifying the correct missing words. Alph and beta particles originate from the Choose... . Protection from radiation is necessary because if radiation passes through the body it can damage Choose... . Exposure to radiation can be limited by increasing the Choose... from the radioactive source.
Answer:
Alpha and beta particles originate from the nucleus, protection from radiation is important because if the radiation passes through the body it can damage cells. Exposure to radiation is often limited by increasing the distance from the radioactive source.
Explanation:
Alpha and beta particles come from unstable atoms during their decay. This radiation is extremely harmful which may damage DNA, causing a high rate of mutation. If we increase the distance of the source of radioactive exposure we will prevent damage.3. Suppose you wanted to design an experiment to test the composition of a mixture that includes sodium phenoxide (NaC6H5O). You know that this solid mixture contains both the NaC6H5O and some inert NaCl, but do not know how much of each is present. You decide to test the composition by titrating with 0.100-M HCl. a. If a 1.000-g sample is 25% NaC6H5O by mass, how many mL of 0.100-M HCl would be required to reach the equivalence point of the titration
Answer:
21.5mL of a 0.100M HCl are required
Explanation:
The sodium phenoxide reacts with HCl to produce phenol and NaCl in a 1:1 reaction.
To solve this question we need to find the moles of sodium phenoxide. These moles = Moles of HCl required to reach equivalence point and, with the concentration, we can find the needed volume as follows:
Mass NaC6H5O:
1.000g * 25% = 0.250g NaC6H5O
Moles NaC6H5O -116.09g/mol-
0.250g NaC6H5O * (1mol/116.09g) = 2.154x10⁻³ moles = Moles of HCl required
Volume 0.100M HCl:
2.154x10⁻³ moles HCl * (1L/0.100mol) = 0.0215L =
21.5mL of a 0.100M HCl are requiredA student dissolves 12.6g of amonium nitrate(NH4NO3) in 250.g of water in a well-insulated open cup. She then observed the temperature of the water fall from 23.0°C to 18°C over the course of 6.1 minutes.
NH4NO3 â NH4+ (aq) + NO3^-(aq)
a. Is this reaction exothermic, endothermic, or neither?
b. If you said the reaction was exothermic or calculate the amount of heat that was released or absorbed by the reaction in this case.
c. Calculate the reaction enthalpy ÎHrxn per mole of NH4NO3.
Answer:
a. Endothermic.
b. [tex]Q_{rxn}=5493.6J[/tex]
c. [tex]\Delta H_{rxn}=35.0kJ/mol[/tex]
Explanation:
Hello there!
In this case, according to the given information for this calorimetry problem, it turns out possible for us to proceed as follows:
a. Due to the fact that the temperature of water goes from 23.0 °C to 18.0 °C, we infer this reaction is endothermic as the ammonium nitrate absorbed heat from the water.
b. Here, we consider the following heat equation:
[tex]Q_{rxn}=-Q_{water}[/tex]
Whereas we solve for the heat of reaction by means of the mass of the solution (both water and ammonium nitrate), the specific heat of the solution (we assume it is equal to that of water) and the temperature change:
[tex]Q_{rxn}=-m_{solution}C_{solution}(T_f-T_i)\\\\Q_{rxn}=-(12.6g+250.g)(4.184\frac{J}{g\°C} )(18.0\°C-23.0\°C)\\\\Q_{rxn}=5493.6J[/tex]
c. Here, we divide the previously calculated heat by the moles of ammonium nitrate (molar mass = 80.043 g/mol) to obtain the enthalpy of reaction per mole of this compound:
[tex]n_{NH_4NO_3}=12.6g*\frac{1mol}{80.043 g}=0.157mol\\\\\Delta H_{rxn}=\frac{5493.6J}{0.157mol} =34898.7J/mol\\\\\Delta H_{rxn}=35.0kJ/mol[/tex]
Regards!
Copper crystallizes in a face-centered cubic unit cell. The density of copper is 8.94 g/cm3. Calculate the length of the edge of the unit cell in pm.
a) 461 pm
b) 361 pm
c) 261 pm
d) 161 pm
e) None of the above
Answer:
361.4 pm is the length of the edge of the unit cell
Explanation:
First, let's calculate the average volume each atom is taking. Start with calculating how many moles of copper we have in a cubic centimeter by looking up the atomic weight. Atomic weight copper = 63.546 Now divide the mass by the atomic weight, getting 8.94 g / 63.546 g/mol = 0.140685488 mol And multiply by Avogadro's number to get the number of atoms: 0.140685488 * 6.022140857x10^23 = 8.472278233x10^22 Now examine the face-centered cubic unit cell to see how many atoms worth of space it consumes. There is 1 atom at each of the 8 corners and each of those atoms is shared between 8 unit cells for for a space consumption of 8/8 = 1 atom. And there are 6 faces, each with an atom in the center, each of which is shared between 2 unit cells for a space consumption of 6/2 = 3 atoms. So each unit cell consumes as much space as 4 atoms. Let's divide the number of atoms in that cubic centimeter by 4 to determine the number of unit cells in that volume. 8.472278233x10^22 / 4 = 2.118069558x10^22 Now calculate the volume each unit cell occupies. 1 cm^3 / 2.118069558x10^22 = 4.721280262x10^-23 cm^3 Let's get the cube root to get the length of an edge. (4.721280262x10^-23 cm^3)^(1/3) = 3.61426x10^-08 cm Now let's convert from cm to pm. 3.61426x10^-08 cm / 100 cm/m * 1x10^12 pm/m = 361.4 pm Doing an independent search for the Crystallographic Features of Copper, I see that the Lattice Parameter for copper at at 293 K is 3.6147 x 10^-10 m which is in very close agreement with the calculated amount above. And since metals expand and contract with heat and cold, I assume the slight difference in values is due to the density figure given being determined at a temperature lower than 293 K.
If my primary DNA strand is ATACCGCAA
a write the complimentary DNA strand
Answer:
TATGGCGTT
Explanation:
Complimentary base pairs:
A-T
C-G
Use the other letter for complimentary strands
How many shapes contains the same text: KTKEIHLPEQMKJAPDEK
In this figure, four shapes contains the same text as in the red oval. The text given in the red oval is KTKEIHLPEQMKJAPDEK.
What is shape?Shape is "the form of an object or its outline, outer boundary or outer surface".
What is text?Text is "a collection of words or letters that are understandable by the reader".
What is an oval?Oval is a rounded and slightly elongated outline or shape like that of an egg.
Hence, four shapes contains the same text as in the red oval.
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Place the following elements in order of decreasing atomic size: lead, phosphorus, oxygen, cesium, barium, and silicon.
Rank from largest to smallest. To rank items as equivalent, overlap them.
Cs, O, P, Si, Ba, Pb
Answer:
Cs> Ba> Pb>Si> P>O
Explanation:
Recall that atomic size decreases across a period and increases down the group.
As we move from Cs to Ba, the atomic size decreases across the period. Lead is larger than silicon since atomic size increases down the group.
Between phosphorus and oxygen, phosphorus is larger than oxygen as you move across the period.
Complete the following nuclear equations. I recommend filling in the atomic number below each symbol. Instead of using superscripts in our answers, put each answer in the corresponding box. A). 54Fe 4He --> 2 1n _____
Answer:
gamma ray
Explanation:
An atom's first 2 energy levels are filled and there are 2 electrons in the third energy
level. It's atomic number is:
Answer:
12
Explanation:
2+8+2=12
atomic no is the No of protons
Answer:
Atomic number is 12.
Explanation:
Atomic number = electrons in filled shells + outermost electrons
= 2 + 8 +2
= 12
2- . the number of waves in n *10 bohr's orbit are
What is molarity?
A. A measure of saturation.
B. A ratio of moles of solvent to moles of solution.
C. A measure of moles.
D. A measure of concentration.
Answer:
Molarity is a measure of concentration
I Hope its right if not so advance sorry :)
The molarity measures the number of moles of the solute present per liter of the solution and it measures the concentration of the solution. option D is correct.
What is molarity?Molarity is the amount or the number of moles present in per liter of the solution it is the unit to measure the concentration of the moles.
Unit of molarity will be moles per liter and the temperature does not affect the molarity of the solution. molarity can be calculated by dividing the concentration of the solution by the molar mass of the given element.
molarity = weight / mass × 1000/ volume in liters.
With the help of this formula, we can calculate the molarity.
Therefore, molarity measures the number of moles of the solute present per liter of the solution and it measures the concentration of the solution. option D is correct.
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Gu
Magnesium metal is reacted with hydrochloric acid to produce
hydrogen gas. A sample of hydrogen gas is collected over water
in a eudiometer at 28.0°C. The atmospheric pressure is 636
mmHg. Determine the pressure (in atm) of the hydrogen gas
produced
Pressure =
atm
The pressure of hydrogen gas is 607.7 mmHg
According of Dalton's law of Partial pressure, the total pressure of a mixture of gases is the sum of the partial pressures of the individual gases in the mixture.
We can now write;
The for hydrogen collected over water, we have a mixture of hydrogen gas and water vapour.
Total pressure = pressure of hydrogen gas + vapour pressure of water
Pressure of hydrogen gas = Total pressure - vapour pressure of water
Pressure of hydrogen gas = 636 mmHg - 28.3 mmHg
Pressure of hydrogen gas = 607.7 mmHg
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According to the Vaporization Heat table, the heat needed for 1 mol of H2O to evaporate at 100°C is 40.7KJ and 44.0KJ/mol is needed to evaporate H2O at 25°C. Thus 44.0-40.7=3.7KJ is the energy needed to heat H2O to 100°C from 25°C.
However, according to the heat capacity of H2O, 3.7KJ will only warm the water by ~+43°C, which is not enough to reach 100°C starting from 25°C!
Am I missing something?!
Suppose you have a material in it's liquid phase. As you give energy to that liquid, the temperature of the liquid will increase gradually, and the relation between the increase of temperature and the given energy is the specific heat.
Now, there is a point, a critical point, where the temperature stops to increase, which means that we are near a change of phase. So from this point on, the energy is not used to increase the kinetic energy of the particles (which would increase the temperature), the energy is used to break the bonds and allow a change of phase, for example, from liquid to gas.
So, we know that if you have a mol of water at 100°C, then you need to add 40.7 kJ of energy to change the phase of the water from liquid to gas phase.
This means that if you have a mol of water and you give that exact energy, the temperature will not change, instead, you now will have a mol of water at the temperature of 100°C.
Similarly with the case at 25°C (which happens for a particular pressure only)
So the heat of vaporization can not really be related to increases in temperature as you thought.
For changes in temperature, you need to use the specific heat.
We know that for water it is:
c = 4.184 J/g*°C = 76.15 J/mol*°C
So, if you want to increase the temperature from 25° to 100°
This means an increase of 75°C of one mol of water.
We just need to multiply the above number by:
1mol*(75°C)
Energy needed = (76.15 J/mol*°C)*1mol*(75°C) = 5,711.25 J
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