Peer Leader: Date: For all problems involving calculations, show your work. Carry the units through each Name: calculation and follow significant figure rules. 1. Calculate the enthalpy of formation of C3H18(g), AH°f, given the following information: C3H18(g) + _O:(g) →_CO2(g) + _H2O(1) AH°»n = -10940 kJ/mol CO:(g) AH°f = -393.5 kJ/mol H;O(1) AH°f = -285.8 kJ/mol

Quinone is an important type of molecule that is involved in photosynthesis. The transport of electrons mediated by quinone in certain enzymes allows plants to take water, carbondioxide, and the energy of sunlight to create glucose. A 0.1964-g sample of quinone (C6H4O2) is burned in a bomb calorimeter with a heat capacity of 1.56 kJ/C. The temperature of the calorimeter increases by 3.2C. Calculate the energy of combustion of quinone per gram and per mole.

Hydrogen sulfide, H2S, is produced during decomposition of organic matter. When 0.5000 mol H2S burns to produce SO2(g) and H2O(l), 281.0 kJ of heat is released. What is this heat in kilocalories?

A 110.-g sample of copper (specific heat capacity = 0.20 J/C g) is heated to 82.4C and then placed in a container of water at 22.3C. The final temperature of the water and copper is 24.9C. What is the mass of the water in the container, assuming that all the heat lost by the copper is gained by the water?

A 45-g aluminum spoon (specific heat 0.88 J/g C) at 24 C is placed in 180 mL (180 g) of coffee at 85 C and the temperature of the two become equal. (a) What is the final temperature when the two become equal? Assume that coffee has the same specific heat as water. (b) The first time a student solved this problem she got an answer of 88 C. Explain why this is clearly an incorrect answer.

An iron skillet weighing 1.63 kg is heated on a stove to 178C. Suppose the skillet is cooled to room temperature, 21C. How much heat energy (in joules) must be removed to affect this cooling? The specific heat of iron is 0.449 J/(gC).

The heat of neutralization, Hneut, can be defined as the amount of heat released (or absorbed), q, per mole of acid (or base) neutralized. Hneut for nitric acid is -52 kJ/mol HNO3. At 27.3C, 50.00 mL of 0.743M HNO3 is neutralized by 1.00 M Sr(OH)2 in a coffee-cup calorimeter. (a) How many mL of Sr(OH)2 were used in the neutralization? (b) What is the final temperature of the resulting solution? (Use the assumptions in Question 11.)

How much heat, in joules and in calories, is required to heat a 28.4-g (1-oz) ice cube from 23.0 C to 1.0 C?

A 0.470-g sample of magnesium reacts with 200 g dilute HCl in a coffee-cup calorimeter to form MgCl2(aq) and H2(g). The temperature increases by 10.9 C as the magnesium reacts. Assume that the mixture has the same specific heat as water and a mass of 200 g. (a) Calculate the enthalpy change for the reaction. Is the process exothermic or endothermic? (b) Write the chemical equation and evaluate H.

Given the following (hypothetical) thermochemical equations: A+B2C;H=447kJA+3D2E;H=484kJ2D+B2F;H=429kJ Calculate H, in kJ, for the equation 4E+5B4C+6F