When 70.4 g of benzamide (C7H7NO) are dissolved in 850. g of a certain mystery liquid X, the freezing point of the solution is 2.7 C lower than the freezing point of pure X. On the other hand, when 70.4 g of ammonium chloride (NH CI) are dissolved in the same mass of X, the freezing point of the solution is 9.9 °C lower than the freezing point of pure X.
Required:
Calculate the van't Hoff factor for ammonium chloride in X.
Answers
Answer:
1.62
Explanation:
From the given information:
number of moles of benzamide \(=\dfrac{70.4 \ g}{121.14 \ g/mol}\)
= 0.58 mole
The molality = \(\dfrac{mass \ of \ solute (i.e. \ benzamide )}{mass \ of \ solvent }\)
\(= \dfrac{0.58 }{0.85 }\)
= 0.6837
Using the formula:
\(\mathbf {dT = l \times k_f \times m}\)
where;
dT = freezing point = 27
l = Van't Hoff factor = 1
kf = freezing constant of the solvent
∴
2.7 °C = 1 × kf × 0.6837 m
kf = 2.7 °C/ 0.6837m
kf = 3.949 °C/m
number of moles of NH4Cl = \(\dfrac{70.4 \ g}{53.491 \ g /mol}\)
= 1.316 mol
The molality = \(\dfrac{1.316 \ mol}{0.85 \ kg}\)
= 1.5484
Thus;
the above kf value is used in determining the Van't Hoff factor for NH4Cl
i.e.
9.9 = l × 3.949 × 1.5484 m
\(l = \dfrac{9.9}{3.949 \times 1.5484 \ m}\)
l = 1.62
Related Questions
A chemist makes up a solution by dissolving 42.0 g of Mg(NO3)2 in enough water to produce a final solution volume of 213 mL. To calculate the molarity of the solution, what additional information is needed
Answers
Answer:
the molar mass of Mg(NO3)2
the mass of the water added the density of the Mg(NO3)2
the volume of water used
Calculate the number of moles of Mg(NO3)2 used to make up this solution. 42.0 g of Mg(NO3)2 is equivalent to___ mol Mg(NO3)2.
Now calculate the molarity of the solution, giving your answer to the correct number of significant digits.
Molarity of Mg(NO3)2 = ___M
HELP!
True or false: When there are zero lone pairs on the central atom, the shape is
symmetrical (assuming all of the bonds are the same).
Answers
PLZ ANSWER QUICK PLZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
Answers
Answer:
D. Atom, Electron, and Proton
Explanation:
Because Atoms are the smallest and they make up everything.
because the Proton, stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10−27 kg, which is 1,836 times the mass of an electron.
Answer:
C
Explanation:
Electrons are the smallest part of matter. Protons are bigger than electrons. And the whole atom is bigger than everything inside it.
How many moles are there in 3.01 x 1024 atoms of argon?
Answers
Answer:
Try this for answer 3082.24
Besides solubility, state two other physical properties that are different for salt and sand.
Answers
Answer:Electrical Conductivity,soluble
Explanation:
Salt is a non-magnetic solid and is soluble in water. Sand is a non-magnetic solid and is insoluble in water.
Electrical Conductivity: Salt is an electrolyte and conducts electricity when dissolved in water or in a molten state. This is because salt dissociates into ions (Na+ and Cl-) that can carry electric current. In contrast, sand is a covalent compound and does not conduct electricity, as it does not dissociate into ions in the same way as salt. Sand is considered an insulator in terms of electrical conductivity.
60 points!! Look at picture please don’t troll
Answers
What is the relationship between cubic centimeters and milliliters?
Answers
Answer:
They are same.
Explanation:
These are the same measurement; there is no difference in volume. The primary difference is that milliliters are used for fluid amounts while cubic centimeters are used for solids. No matter what is being measured, 1 cc always equals 1 mL.
if 650J heat is absorbed by a system and 450J work is done on the system, then find the change in internal energy of the system
Answers
Answer: 380 J. Please mark
Explanation:
4.The scientific method is ________________ reasoning. You can make ______________ explanations for something that you are observing in the world.
Answers
Answer:
The scientific method is a system of reasoning. You can make reasonable explanations for something that you are observing in the world.
Explanation:
Which is the formula mass of (NH4)2SO4?
0 96.07 amu
114.12 amu
O 116.17 amu
132.17 amu
Answers
Answer:
D. 132.17 amu
Explanation:
The formula mass of a compound can be determined from the formula of the compound thus, from the number each elements present. The formula mass of (NH₄)₂SO₄ is 132.17 amu.
What is formula mass?
Formula mass of a compound is the mass calculated from its formula. Each elements has a definite mass called its atomic mass expressed in g/mol or amu.
Mass number of an element is the sum of number of its protons and neutrons. The actual mass of an element is calculated with respect to the mass of 1/12th of Carbon-12 and it is called relative mass.
Here, the atomic mass of N = 14.006 amu
mass of H = 1.008 amu.
There are 4 hydrogen thus 4 × 1.008 = 4.008 u.
The mass of two units of NH₄ is = (14.006 + 4.008) × 2
= 36.028 u.
Atomic mass of sulfur = 32.6 amu
atomic mass of oxygen = 15.9 amu.
Thus for 4 oxygens = 15.9 × 4 = 63.6 u
The mass of SO₄ unit = 32.06 + 67.6 = 96.2u
Thus the total mass of (NH₄)₂SO₄ = 96.2 + 36.028
= 132.17 amu
Hence, the formula mass of (NH₄)₂SO₄ is 132.17 amu. Thus, option D is correct.
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N 2H 4 + H202 N2 + H 20
Answers
Answer:
N2 + H20
Explanation:
chemical equation balancer
MULTIPLE CHOICE QUESTION
How many grams of Al203 were
decomposed?
287.13
200g
888g
1148.52g
Answers
287.13 grams of Al₂O₃ were decomposed. Therefore, option A is correct.
What is molar mass ?The term molar mass is defined as the mass in grams of one mole of the compound. A mole of any substance is 6.022 × 10²³ molecules. It is called as Avogadro's number. The molar mass is a bulk property, it is not molecular, property of a substance.
2Al₂O₃ ⇒ 4Al + 3O₂
Thus, 4 mol of Al combine with 3 mol of oxygen to form 2 mol of Al₂O₃.
2 mol of Al corresponds to 2 × 27 = 54g
Thus, the weight of Al used in the reaction is 108 g.
Molar mass of Al₂O₃ is 101.96g/mol.
5.63 moles of Al = 5.63 × 54 / 101.96
= 287.13 grams
Thus, 287.13 grams of Al₂0₃ were decomposed, option A is correct.
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The Statue of Liberty is 151 ft tall. Calculate its height in meters.
Answers
Answer: 151 ft = 46.02 meters
Explanation:
Determine the molarity (M) of 0.2074 g of calcium hydroxide, Ca(OH)₂ (74.09 g/mol), in 40.00 mL of solution.
Answers
Answer:
M=0.06998 mol/L
Explanation:
what is the definition of oxidation
Answers
Answer:
oxidation is an energy that produces reaction in a living cell.
Answer:
the process or result of oxidizing or being oxidized.
Explanation:
A patient needs 3.30×10−2 g of a sulfa drug. There are 5.00 mg tablets in stock. How many tablets should be given?
Answers
Answer: 6.6.0gdm^-3
Bamstep
Calculate the relative atomic mass of M
Answers
Answer:
63.55
Explanation:
relative atomic mass=(mass of isotope1×relative abundance)+(mass of isotope 2×relative abundance)/100
r.a.m=(62.93×69.09)+(64.93×30.91)/100
=(4347.8337)+(2006.9863)/100
=6354.82/100
=63.55
Match each energy type with the source it uses.
Solar
?
Nuclear reactions
Hydropower
?
Moving water
Geothermal
?
Sun's rays
Biomass
?
Plants
ASAP HELL
Answers
Hydropower: Moving water
Solar: Sun’s rays
Biomass: Plants
The energy exists in many different forms. Each form of energy can be converted or changed into the other forms. The geothermal energy denotes the thermal energy.
What is solar energy?The energy produced from the sun is called the solar energy. The heat and light which come from the sun is the solar energy. The solar energy play an important role in reducing the emissions of green house gases and also control the climate change.
The biomass is known as the fuel obtained from the organic matter waste of the living organisms such as plant waste, animal waste and municipal wastes. It is the fuel developed from plants.
The hydropower is the largest source of renewable energy which uses the moving water to produce electricity. The energy which is generated from the heat within the earth is called the Geothermal energy.
Thus,
Solar - sun's rays
Moving water - Hydropower
Plants - Biomass
Nuclear reactions - Geothermal
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Is burning physical or chemical change?
Answers
Answer:
a chemical change
Explanation:
lighting a match is a chemical change. chemical reactions cause chemical change. in a chemical reaction two or more substances, called the reactants, form different substances called products. hope this helped :)
A mixture of 5L of H2 and 3L O2 reacts to form H2O (g) at constant T and P .Find the
volume of H2O gas obtained. 2H2 (g) + O2(g)
2H2O(g)
Answers
The volume of H₂O = 5 L
Further explanationGiven
5L of H₂ and 3L O₂
Reaction
2H₂ (g) + O₂(g) ⇒2H₂O(g)
Required
The volume of H₂O
Solution
Avogadro's hypothesis:
In the same T,P and V, the gas contains the same number of molecules
So the ratio of gas volume will be equal to the ratio of gas moles
mol H₂ = 5, mol O₂ = 3
Find limiting reactantsFrom equation, mol ratio H₂ : O₂ = 2 : 1, so :
\(\tt H_2\div O_2=\dfrac{mol~H_2}{coefficient}\div \dfrac{mol~O_2}{coefficient}\\\\=\dfrac{5}{2}\div \dfrac{3}{1}=2.5\div 3\rightarrow H_2~limiting~reactant(smaller~ratio)\)
Find volume H₂Omol H₂O based on mol H₂, and from equation mol ratio H₂ : H₂O=2 : 2, so mol H₂O = 5 mol and the volume also 5 L
A beam of x-ray of wavelength 0.071 nm is diffracted by (110) plane of rock salt with lattice constant (a) 0.28nm. find the glancing angle for the second order diffraction
Answers
The glancing angle for the second order diffraction of X-rays with a wavelength of 0.071 nm diffracted by the (110) plane of rock salt with a lattice constant of 0.28 nm can be calculated using Bragg's law:
2d sinθ = nλ
where d is the interplanar spacing of the (110) plane, n is the order of the diffraction, λ is the wavelength of the X-rays, and θ is the glancing angle.
For the second order diffraction (n = 2), we have:
2d sinθ = 2λ
The interplanar spacing of the (110) plane can be calculated using the formula:
d = a/√(h^2 + k^2 + l^2)
where a is the lattice constant, and h, k, and l are the Miller indices of the (110) plane. For rock salt, h = 1, k = 1, and l = 0 for the (110) plane.
Substituting the values given in the problem, we get:
d = 0.28 nm / √(1^2 + 1^2 + 0^2) = 0.14 nm
Substituting the values for d, n, and λ, we get:
2(0.14 nm) sinθ = 2(0.071 nm)
Simplifying, we get:
sinθ = 0.51
Taking the inverse sine, we get:
θ = 30.2 degrees
Therefore, the glancing angle for the second order diffraction is approximately 30.2 degrees.
What is the change in temperature after 840 Joules is absorbed by 10.0g of water is heated?(Specific heat of water is 4.184 J/g °C)
Answers
Answer:
dt=20.08
Explanation:
Q=msdt
840=10*4.184*dt
dt=840/(10*4.184)
dt=20.08
Use the data in the table below to answer the following questions. The true value for this data set is 5.68g.
Answers
1) The student which is neither precise nor accurate is student B
2) The student which is most accurate on any single trial is student A
3) The student that is both precise and accurate is student C
4) The student which is precise but not accurate is student D
What is precision and accuracy?The term precision has to do with the fact that the values of the measurement are close together. Precise values do not scatter a lot. They vary within a narrow range.
An accurate measurement is one that is close to the true value. This means that it does not differ so much from the true value of the measurement.
Hence;
1) The student which is neither precise nor accurate is student B
2) The student which is most accurate on any single trial is student A
3) The student that is both precise and accurate is student C
4) The student which is precise but not accurate is student D
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The reaction of nitrogen and hydrogen to make ammonia is important because it provides fertilizer for growing food, and is because ammonia is needed to make other nitrogen-containing compounds. At room temperature, ∆G° and ∆H° for the reaction are both negative.
N2(g) + 3 H2(g) --> 2 NH3(g)
Which two of the following statements about this reaction are true?
- Adding an appropriate catalyst makes the reaction more spontaneous
- Increasing the temperature lowers the activation energy of the reaction
- Increasing the temperature makes the reaction less spontaneous
- The entropy change for the reaction is positive
- Increasing the pressure makes the reaction more spontaneous
Answers
The two statements that are true about the reaction are:
Adding an appropriate catalyst makes the reaction more spontaneous Increasing the temperature lowers the activation energy of the reactionWhat is a catalyst?A catalyst is described as a substance that speeds up a chemical reaction, or lowers the temperature or pressure needed to start one, without itself being consumed during the reaction.
If we happen to increase the temperature, it provides more kinetic energy to the reactant molecules and this makes it more likely to overcome the activation energy barrier and engage in the reaction.
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If the magnetic energy stored by a 0.50 H inductor is 3.6 J, what is the current through it?
A. 0.13 A
B. 0.90 A
C. 1.8 A
D. 3.8 A
E. 5.4 A
Answers
The current passing through the inductor is 3.8 A. The correct option is D. 3.8 A
Energy stored in a magnetic fieldFrom the question, we are to determine the current passing through the inductor.
From the formula, for the energy stored in a magnetic field
E = 1/2LI²
Where E is the energy
L is the inductance
and I is the current
From the given information,
E = 3.6 J
L = 0.50 H
Putting the parameters into the formula, we get
3.6 = 1/2 × 0.50 × I²
3.6 = 0.25 × I²
I² = 3.6 ÷ 0.25
I² = 14.4
I = √14.4
I = 3.7947
I ≅ 3.8 A
Hence, the current passing through the inductor is 3.8 A. The correct option is D. 3.8 A
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600 650 700T (K)k (Ms) 0.533 2.88 14.2800 10001200153 5.20 10 4.77 10¹68.The conversion of substance A to substance B has E= -35 kJ mol' and an activation enery, E., of 25 kJ mol. Sketch areaction diagram, and on it clearly indicate A, B, the activated complex (C), E and E..
Answers
Answer:
Explanation:
Here, we want to plot the reaction diagram
As we can see, the energy change is negative, which indicates an exothermic reaction.
We have the reaction diagram as follows;
Can someone please convert this for brainiest answer
2.4 x 10^24 atoms c to grams
Answers
Answer:
48 g C
Explanation:
To find the grams, you need to (1) convert atoms to moles (using Avogadro's Number) and then (2) convert moles to grams (using atomic mass). It is important to arrange the conversions in a way that allows for the cancellation of units. The final answer should have 2 sig figs to match the sig figs of the given value.
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
Atomic Mass (C): 12.011 g/mol
2.4 x 10²⁴ atoms C 1 mole 12.011 g
----------------------------- x -------------------------------- x --------------- = 48 g C
6.022 x 10²³ atoms 1 mole
The city council of Centerville pass a law requiring all new buildings to be outfitted with low-flow toilets instead of regular toilets. The low-flow toilets use approximately 2 less gallons of water per flush. What will be the most likely effect of this new law?
A.
increase in the habitat size for the area's wildlife
B.
decrease in the amount of acid rain falling in the area
C.
pollution of the local groundwater
D.
conservation of local freshwater supplies
Answers
this is the only answer i see that would make sense to the question :)
Answer:
probably b
Explanation:
Chemistry Help Please! Worth a lot of points!
1. Joseph Priestly was the first scientist to be able to prepare pure oxygen gas. He did this by heating mercuric oxide as shown in the reaction below. Answer the question related to the reaction.
2HgO(s) = 2Hg(l) + O2(g)
a.What volume of oxygen gas would be produced at STP through the decomposition of 5.36 grams of HgO? It is not collected over water!
b. What volume of oxygen gas would be produced at 23o and 0.975 atm by the decomposition of 5.36 grams of HgO?
c. What volume of oxygen gas would be collected over water at 23oC and 0.975 atm by the decomposition of 5.36 grams of HgO?
2. How many grams of water will form through the reaction of 550 mL of 2.5 M HCl and an excess amount of Ca(OH)2?
Ca(OH)2(aq) + 2HCl(aq) = CaCl2(aq) + 2H2O(l)
a. How many grams of calcium chloride will form if 250 mL of 2.0 M Ca(OH)2 reacts with 350 mL of 2.5 M HCl? Make sure to determine the limiting reagent!
3. Sam conducted an experiment where he reacted 5.0 grams of magnesium with an excess amount of oxygen gas to form magnesium oxide (MgO). When he conducted this in the lab, he obtained 8.06 grams of magnesium oxide.
a. Write and balance the chemical reaction.
b. Use stoichiometry to predict how many grams of magnesium oxide should form.
c. What is the theoretical yield?
d. What is the actual yield?
e. Calculate the percent yield.
4. Na(s) + Br2(L) = NaBr(s) (not balanced)
b.If 3.05 grams of sodium react with 10.0 grams of diatomic bromine, what is the excess reagent AND how many moles of excess reagent are present after the reaction?
c. How many grams of sodium bromide are formed?
Answers
Answer:
A.
1. a. 11.28L O2
b. 24.3L O2
c. 19.83L O2
2. a. 5.6 grams CaCl2
3. a. 2Mg + O2 = 2MgO
b. 8.06 grams MgO
c. 8.06 grams MgO
d. 8.06 grams MgO
e. 100%
4. a. 2Na + Br2 = 2NaBr
b. Excess reagent: Bromine; 0.5 moles
c. 10.6 grams NaBr
all the questions 1. What contribution did de Broglie make to the development of the modern model of the atom? (A)Observed the effect of bombarding thin gold foil (and other metal foils) with alpha radiation from radioactive substances. 60 m B. Discovery of the nucleus C. Discovered that atoms and molecules emit energy only in certain discrete quantities, or quanta. D. Discovered negatively charged particles by cathode ray tube experiment E. Described the wave properties of particles
Answers
De Broglie contributed to the development of the modern model of atoms by describing the wave properties of particles. Option E.
De Broglie's contribution to atomic theoryLouis de Broglie was a French physicist who made significant contributions to the development of quantum mechanics.
In his doctoral thesis, he proposed that particles, such as electrons, have both particle-like and wave-like properties. This idea became known as wave-particle duality and laid the foundation for the development of the modern model of the atom.
According to de Broglie's theory, particles can exhibit wave-like behavior and have a wavelength that is inversely proportional to their momentum.
This theory was later experimentally confirmed in a series of experiments that demonstrated the diffraction of electrons and other particles.
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