Lesson13

What is the oxidation number of carbon in C2O4?

+4

What is the oxidation number of phosphorus in PO4-3?

+5

A 28.4 g sample of an unknown metal is heated to 39.4 °C, then is placed in a calorimeter containing 50.0 g of water. Temperature of water increases from 21.00 °C to 23.00 °C. What is the specific heat of this metal in this problem?

0.898 J/g °C.

The units for specific heat are.

J/g °C

Heat is measured in

Joules

Which is a device used to measure the heat absorbed or released during a chemical or physical process?

calorimeter

If an iron ball is placed in a calorimeter at 40.0 °C and the water inside the calorimeter is 40.0 °C, the heat will

not flow at all since the two are already at thermal equilibrium.

What mass of benzene is cooled from 83.8 °C to 77.1 °C when 167 J of energy is transferred out of the system? (The specific heat of benzene is 1.740 J/g °C).

14.3 g

How much heat is lost when a solid iron nail weighing 23.00 g cools from 675.0 °C to 133.6 °C? (The specific heat of Fe is 0.450 J/g °C).

5603 J.

A piece of aluminum metal at an initial temperature of 97.3°C was placed in a calorimeter containing 49.0g of water at an initial temperature of 22.0°C. The two were allowed to come to thermal equilibrium and the final temperature was 24.1°C. The specific heats of water and aluminum are 4.184 J/g °C and 0.902 J/g °C, respectively. What was the mass of the Al piece that was added?

6.52 g

How much heat is released when 27.6 g PCl3 cools from 83.1 °C to 55.6 °C? (The specific heat of PCl3 is 0.874 J/g °C).

663 J.

If 18.9 J of heat was gained when 2.6 g of O2 was heated, what was the temperature change that occurred? (The specific heat of O2 is 0.954 J/g °C)

7.6 °C.

Which substance is being oxidized in the following reaction? 4Na + O2 → 2Na2O

Na

Which substance is the oxidizing agent in the following reaction? 2H2 + O2 → 2H2O

O2

The specific heat capacity of an object depends in part on its

mass