4.13 Unit Test: Chemical Thermodynamics - Part 1

A chemical reaction is carried out in a closed container. The energy absorbed by the chemical reaction is 200 kJ. What is the energy liberated from the air or the walls of the container?

200 kJ

In a calorimeter, 10.0 g of ice melts at 0oC. The enthalpy of fusion of the ice is 334 J/g. How much heat was absorbed?

3.34 kJ

Which statement is a correctly written thermochemical equation?

4Fe(s)+3O2(g)→2Fe2O3(s), ΔH=−3,926kJ

How much heat do you need to raise the temperature of 150 g of gasoline from −30°C to −15°C ? Picture of Table Included.

5.00 kJ

In a calorimeter, 20 g of ice absorbs heat with an enthalpy of fusion of 334 J/g. What is the heat absorbed? q=mΔHf Picture Of Table Included.

6.68 kJ

Which statement is true?

In an exothermic reaction, the energy of the products is less than the energy of the reactants.

In which thermochemical equations would the ΔH be considered a heat of solution?

NH4NO3(s)→NH4+(aq)+NO3-(aq), ΔH=+25.7 kJ/mol

Unless otherwise instructed, you may use a scientific calculator and refer to the periodic table in the Chemistry: Problems and Solutions book for this question. Which example is an exothermic reaction?

condensation

Two hundred grams of a substance requires 0.52 kJ of heat to raise its temperature from 25°C to 45°C. Use the table to identify the substance. q=mCΔT. Mass (m) is in grams. Temperature is in degrees Celsius. Picture of Graph included.

gold

This diagram would represent the enthalpy changes in which example?

hot pack

Which parameter is measured directly in a coffee-cup calorimeter?

temperature

Which term measures thermal energy in an object?

temperature

You have a series of four chemical reactions (1→2→3→4)(1→2→3→4). How do you calculate the ΔH2ΔH2 if you know the other ΔHΔH values?

ΔH2=ΔH4−(ΔH1+ΔH3)

What is likely to be true about the ΔH for this reaction? C6H6 (s) → C6H6 (l)

∆H>0

Consider these equations: 2S(s)+3O2(g)→2SO3(g)2S (s) + 3O2 (g)→2SO3 (g), ΔH=−792kJΔH = −792 kJ 2S(s)+2O2(g)→2SO2(g)2S (s) + 2O2 (g)→2SO2 (g), ΔH=−594kJΔH = −594 kJ 2SO2(g)+O2(g)→2SO3(g)2SO2 (g) + O2 (g)→2SO3 (g), ΔH=?ΔH =? What is the missing ΔHΔH?

−198kJ

The reaction 2NO(g) → N2(g) + O2(g) has a ΔH=−180.5kJ . How much heat will be required to produce 44.8 L of NO by the reverse reaction?

180.5 kJ

Which type of substance would be best for use in a heating system?

a liquid with a high specific heat

How much heat is given off when 16 g liquid methanol (CH3OH) at its freezing point changes to solid methanol? (methanolΔHf=3.16kJ/mol)

1.58 kJ

Two objects (A and B) of the same temperature are in contact with each other. Which statement is true?

Although the molecules collide, no heat transfers because there is no temperature difference between the objects.

What is the change in enthalpy when 250 g of water vapor condenses at 100oC? (ΔHv=40.67kJ/mol)

−565kJ