Introduction to Thermo-Chemistry Lesson

Thermochemistry Test Review

Q = mcΔt

• Q = energy (J)

• m = mass (g)

• c = specific heat (J/g*C)

• Δt = CHANGE in temperature

Multiple Choice

How much heat is needed to raise the temperature of 50 g of iron by 15°C? (specific heat of iron = 0.444 J/g°C)

• 333 J

• -333 J

• 33300 J

• -3330 J

Multiple Choice

What is the specific heat of a substance with a mass of 550g that requires 10,000 J to increase temp. by 20*C.

• 0.91

• 1.1

• 363.63

Multiple Choice

What is the mass of a sample of water that releases 150,000J as it cools down from 100*C to 0*C. (c = 4.184)

• -358.51 g

• 278.933 g

• 358.51 g

Multiple Choice

What is the final temp of a 500g sample of platinum ( c=0.133), that starts at 100*C and absorbs 1,662.5J of heat?

• 75*C

• 125*C

• 25*C

• -25*C

Δ = Final - Initial

Multiple Choice

Use the H_f values in the table below to answer questions a and b about the following reaction.

CO_2(g) + N_2(g) ⟶ NO_(g) + CO_(g) ΔH = ?

Formula kJ/mol

CO(g) -110

CO2(g) -394

NO(g) 90

a) Calculate Hrxn for the reaction.

• 370kJ/mol

• 374kJ/mol

• 333kJ/mol

• 335KJ/mol

Multiple Choice

This question is about the reaction given below.

CO(g) + H₂O(g) ⇌ CO₂(g) + H₂(g)

Enthalpy data for the reacting species are given in the table.

The standard enthalpy change for this reaction of carbon monoxide and steam is

• +42 kJ mol⁻¹

• −42 kJ mol⁻¹

• +262 kJ mol⁻¹

• −262 kJ mol⁻¹

Multiple Choice

Between which points is the temperature of the substance increasing?

• A-B only.

• A-B, C-D, E-F

• B-C only.

• B-C, D-E

Multiple Choice

In which segment is the kinetic energy remaining constant?

• A-B
• B-C
• C-D
• E-F

Multiple Choice

Baking pizza in the oven

• endothermic

• exothermic

Multiple Choice

Ice cubes in your glass of soda melt.

• endothermic

• exothermic

Multiple Choice

Your family uses candles to see when the electricity goes out.

• exothermic

• endothermic

Multiple Choice

A sunflower makes food during photosynthesis.

• exothermic

• endothermic

Multiple Choice

Energy is __________ in this reaction

• absorbed

• released

Multiple Choice

What type of reaction is this?

• Exothermic

• Endothermic

• Energy Producing

• No way to tell

Multiple Choice

What is the Heat of Reaction $$\Delta H$$  for this reaction?

• -200 KJ

• 200 KJ

• 400 KJ

• -300 KJ

Multiple Choice

This energy curve is best described as an...

• endothermic reaction

• exothermic reaction

Enthalpy

• is the measure of heat transfer (ΔH) CHANGE IN HEAT ENERGY

• Positive ΔH is an endothermic reaction, the system added heat

• Negative ΔH is an exothermic reaction, the system lost heat

Multiple Choice

q = +6,000 J

• Endothermic

• Exothermic

Multiple Choice

2H₂O + 5500J --> 2H₂ + O₂

• Endothermic

• Exothermic

Multiple Choice

Heat of reactants = 1500J

Heat of products = 400J

Endothermic or exothermic?

• exothermic

• endothermic

Multiple Choice

F₂ + 2NaCl --> 2NaF + Cl₂ + 400J

• Endothermic

• Exothermic