End-Quarter 1 Test Review

Identify which number step is the rate-determining step.

Step 3

A system absorbs 105 kJ of heat from its surroundings while doing 29 kJ of work on

the surroundings. Calculate ΔE.

76 kJ

2 H2(g) + O2(g) → 2 H2O(g)

If hydrogen is burning at a rate of 0.85 mol/s, what is the rate of consumption of

oxygen?

0.43 mol/s

2 Mg(s) + O2(g) → 2 MgO(s) ΔH = -1204 kJ

How many grams of MgO are produced during an enthalpy change of -96.0 kJ?

6.43 g MgO produced

NH4+(aq) + NO2

-(aq) → N2(g) + H2O(l)

Write the rate law for this reaction.

Rate = k [NH4+] [NO2

−]

CH3OH(l) + O2(g) → CO2(g) + 2 H2O(l) ΔH = -726.5 kJ

What is the enthalpy of the reverse reaction?

+726.5 kJ (reverse rxn, reverse sign)

NH4+(aq) + NO2

-(aq) → N2(g) + H2O(l)

Calculate the value of k. Include appropriate units.

2.7 x 10-4 L/mol·s

CH3OH(l) + O2(g) → CO2(g) + 2 H2O(l) ΔH = -726.5 kJ

If the reaction were written to produce H2O(g) instead of H2O(l), would you expect

the magnitude of ΔH to increase, decrease, or stay the same? Explain.

Decrease (smaller negative); vaporization is an endothermic process, thus adding a

positive value to the current enthalpy

NH4+(aq) + NO2

-(aq) → N2(g) + H2O(l)

What would the rate be when [NH4+] is

4.00 M and [NO2−] is 2.00 M?

0.0022 mol/L·s

When a 9.55-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter, the temperature rises from 23.6°C to 47.4°C. Calculate the ΔHsoln in kJ mol-1 for the process. Assume

the specific heat of the solution is 4.18 J g-

1 °C-1.

qcal = 10.9 kJ; ΔHsoln = -45.7 kJ/mol

NH4+(aq) + NO2

-(aq) → N2(g) + H2O(l)

Using experiment #1, how long would it take in minutes until 0.050 M NO2

- remained?86 min

H2(g) + F2(g) → 2 HF(g)ΔH = -537 kJC(s) + 2 F2(g) → CF4(g) ΔH = -680 kJ

2 C(s) + 2 H2(g) → C2H4(g) ΔH = +52.3 kJ

Calculate the ΔH for the reaction of ethylene with F2:

C2H4(g) + 6 F2(g) → 2 CF4(g) + HF(g)

2,390 kJ (2,381.7 kJ)

What happens to the probability of an elementary reactions as its molecularity

increases? Explain.

The probability decreases; less likely to 1) collide with 2) proper orientation and 3)

sufficient energy

Write a balanced thermochemical equation for the formation of NH4NO3(s).

2N2(g) + 2H2(g) + O2(g) → NH4NO3(s) ΔH = -365.6 kJ

How many intermediates are formed in this reaction?

Two

Which color line represents the

highest temperature?

purple

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