AP Chemistry Unit 6 Practice

Instructions

  1. Choose a topic, then start. Mixed review includes all nine topics.
  2. Select one answer, or enter a signed number and choose its unit. Use + or - for heat and enthalpy answers.
  3. Submit once per question. Read the explanation, then continue. Your score counts correct answers; a significant figure note does not remove a point.
  4. At the end, Try again shuffles the questions and answer choices. Choose another topic to build a new set.

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AP Chemistry · Unit 6

Catch up at your own pace.

Choose one topic for six questions, or Mixed review for all 54. Read the feedback after each answer.

No timer. Use scratch paper and a calculator. The thermochemistry reference is below.

Reference

Heat and reaction enthalpy

q = mcΔT; ΔT = Tfinal − Tinitial.

Specific heat capacity of water: 4.18 J/(g·°C).

At constant pressure with only pressure-volume work, system heat equals its enthalpy change. For an insulated calorimeter with negligible cup heat capacity:

qreaction = −qsolution; ΔH = qreaction/nreaction.

ΔH°rxn = Σ ΔH°f(products) − Σ ΔH°f(reactants).

ΔH = Σ bonds broken − Σ bonds formed.

Every sum includes balanced coefficients. ΔH values in kJ/mol refer to one mole of reaction as written, unless a named substance is specified. Heat q is in J or kJ.

The standard enthalpy of formation of an element in its standard state is 0.

Average gas-phase bond enthalpies

BondBond enthalpy (kJ/mol)
H-H436
Cl-Cl243
H-Cl431
O=O498
O-H463
N≡N945
N-H391

Standard enthalpies of formation at 298 K

SpeciesΔH°f (kJ/mol)
CH4(g)−74.8
CO2(g)−393.5
H2O(l)−285.8
H2O(g)−241.8
CaCO3(s)−1206.9
CaO(s)−635.1
O2(g), H2(g), N2(g), C(s, graphite)0

Phase changes of water

q = nΔHphase. Fusion: +6.01 kJ/mol. Vaporization: +40.7 kJ/mol.

Phase values apply at the normal melting and boiling points, respectively. They are not the difference between the 298 K gas and liquid formation values.

Keep extra digits in your work and round only the final answer. Use a + sign for heat entering the system and a − sign for heat leaving it.

Aligned practice for AP Chemistry CED topics 6.1 to 6.9. Original ZornScience questions.

About this activity

Review AP Chemistry Unit 6, Thermochemistry, with 54 original questions. Each answer gets an explanation right away, and your score is broken down by topic.

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