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3 years ago

What is another way of describing a freezing point change?

Chemistry

2 answers:

Paladinen [302]3 years ago

7 0

Melting is equivalent to freezing: a temperature when a solid become a liquid.

andrew-mc [135]3 years ago

6 0

The girl on top is correct

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Nitrogen forms a surprising number of compounds with oxygen. A number of these, often given the collective symbol NOx (for "nitr

kvv77 [185]

Answer:

9.2

Explanation:

Let's do an equilibrium chart of this reaction:

2NO(g) + O₂(g) ⇄ 2NO₂(g)

4.9 atm 5.1 atm 0 Initial

-2x -x +2x Reacts (stoichiometry is 2:1:2)

4.9-2x 5.1-x 2x Equilibrium

The mole fraction of NO₂ (y) can be calculated by the Raoult's law, that states that the mole fraction is the partial pressure divided by the total pressure:

y = 2x/(4.9 - 2x + 5.1 -x + 2x)

0.52 = 2x/(10 - x)

2x = 5.2 -0.52x

2.52x = 5.2

x = 2.06 atm

Thus, the partial pressure at equilibrium are:

pNO = 4.9 -2*2.06 = 0.78 atm

pO₂ = 5.1 - 2.06 = 3.04 atm

pNO₂ = 2*2.06 = 4.12 atm

Thus, the pressure equilibrium constant Kp is:

Kp = [(pNO₂)²]/[(pNO)²*(pO₂)]

Kp = [(4.12)²]/[(0.78)²*3.04]

Kp = [16.9744]/[1.849536]

Kp = 9.2

4 0

2 years ago

45 The mass of an unidentified metal sphere is 133 grams. Students determine the

Lisa [10]

Answer:

D Cobalt

Explanation:

The volume of the sphere is 40 -25 = 15 cm^3

Density = mass/volume = 133 gm / 15 cm^3 = 8.87 gm/cm^3

which corresponds to Cobalt from the chart

7 0

2 years ago

How many moles are in 5.22 x 10^24 atoms<br> of H2O?

alexgriva [62]

Answer: 5.22×10^24ato^2 H2O

Explanation:

6 0

3 years ago

Nitric oxide (NO) can be formed from nitrogen, hydrogen and oxygen in two steps. In the first step, nitrogen and hydrogen react

son4ous [18]

Answer:

ΔH = - 272 kJ

Explanation:

We are going to use the fact that Hess law allows us to calculate the enthalpy change of a reaction no matter if the reaction takes place in one step or in several steps. To do this problem we wll add two times the first step to second step as follows:

N2(g) + 3H2(g) → 2NH3(g) ΔH=−92.kJ Multiplying by 2:

2N2(g) + 6H2(g) → 4NH3(g) ΔH=− 184 kK

plus

4NH3(g) + 5O2(g) → 4NO(g) +6H2O(g) ΔH=−905.kJ

__________________________________________________

2N2(g) + 6H2(g) + 5O2(g)→ 4NO(g) + 6H2O(g) ΔH = (-184 +(-905 )) kJ

ΔH = -1089 kJ

Notice how the intermediate NH3 cancels out.

As we can see this equation is for the formation of 4 mol NO, and we are asked to calculate the ΔH for the formation of one mol NO:

-1089 kJ/4 mol NO x 1 mol NO = -272 kJ (rounded to nearest kJ)

5 0

3 years ago

What does Hess's law state can be done in order to be able to react solid magnesium with oxygen gas safely (that is, without exp

aleksley [76]

Answer:

C. The reaction can be broken down and performed in steps

Explanation:

Hess's Law of Constant Heat Summation states that irrespective of the number of steps followed in a reaction, the total enthalpy change for the reaction is the sum of all enthalpy changes corresponding to all the steps in the overall reaction. The implication of this law is that the change of enthalpy in a chemical reaction is independent of the pathway between the initial and final states of the system.

To obtain MgO safely without exposing magnesium to flame, the reaction sequence shown in the image attached may be carried out. Since the enthalpy of the overall reaction is independent of the pathway between the initial and final states of the system, the sum of the enthalpy of each step yields the enthalpy of formation of MgO.

3 0

2 years ago