DOL: 4/17-4/18_endothermic&exothermic

When a student uses the equation, mass multiplied by change in temperature multiplied by specific heat, what is being calculated? q=m×C×△T

• heat gain or heat loss

• a phase change

• stored energy

• heat convection

How much energy is needed to raise the temperature of 5.0 grams of lead from 25°C to 35°C? q=c×m×△T [specific heat (c) = 0.129 J/(g•°C)]

• 6.45 J

• 16.1 J/(g•°C)

• 16.1 J

• 6.45 J/(g•°C)

Specific heat is defined as the amount of energy needed to raise the temperature of 1 gram of a substance by 1°C. If the mass of each substance were equal, which substance would heat the fastest?

• aluminum

• Graphite

• Silver

• Iron

The table below shows the standard enthalpy of formation for each of three substances.

CaCO3 decomposes according to the equation CaCO3(s) −→− Δ CaO(s) + CO2(g).

What is the enthalpy of reaction?

• 178.3 kJ

• 571.8 kJ

• −1029 kJ

• −2236 kJ

The chemical equation below shows the production of HCl and Br.

HCl ΔHf=−92.0 kJ/mol HBr ΔHf=−36.4kJ/mol

Cl2(g)+2HBr(g)→2HCl(g)+Br2(g)

Given the standard enthalpies of formation, what is the enthalpy change for the given chemical equation?

• ΔHf=±111.2 kJ/mol

• ΔHf=−27.8 kJ/mol

• ΔHf=±55.6 kJ/mol

• ΔHf=−128.4 kJ/mol