chem sem 2 4.05

The amount of heat needed to raise 25 g of a substance by 15°C is 293 J. What is the specific heat of the substance? Use the equation C = q/mΔT.

0.78 J/g-°C

The temperature of 100 g of liquid water in a calorimeter changes from 25°C to 50°C. How much heat was transferred? Use the equation C = q/mΔT. The specific heat of liquid water is 4.18 J/g-°C.

10.5 kJ

The mass (m) is in

grams

Substances do vary in their ability to store thermal energy. This property is called

heat capacity

The heat capacity is an

indication of how fast an object heats or cools

Heat (q; in joules) can

be calculated with the equation q = mCΔT

Temperature is in degrees

Celsius

100 g of a substance absorbs 1.17 kJ when its temperature increases by 30ºC. What is the substance?

Given: q = 1.17 kJ or 1,170 J m = 100 g delta TΔT = 30ºC Unknown: C = ? Write equation for specific heat : C=q/mΔT Substitute values into the equation: C=(1,170J) / (100g)(300C) C = 0.39J/g−(zero squared)0C Look up the specific heat in a table of specific heat values to identify the substance. Copper: 0.39 the substance is copper

A 50 g copper rod absorbs 585 J of heat to raise its temperature by 30°C. What is the specific heat of copper?

Given: q = 585 J, m = 50 g, ΔT = 30°C Unknown: C Write the equation for specific heat: C = q/mΔT Substitute values into the equation: C = (585 J)/(50 g)(30°C) = 0.39 J/g-°C

Which of the following statements is true about the specific heat capacities of various substances?

Liquid water has a relatively high specific heat capacity compared to most other substances

What is the difference between heat capacity and specific heat?

Only specific heat accounts for mass

Substances A-D have the following specific heats (J/g-°C): A = 0.90, B = 1.70, C = 2.70, D = 4.18. When equal masses are heated to the same temperature, which substance will cool the fastest?

substance A

heat capacity

the ability of substances to store or release thermal energy

Specific heat (C) is

the amount of heat energy that it takes to raise the temperature of one gram of a specific substance by one degree Celsius

specific heat capacity

the amount of heat needed to raise the temperature of a substance 1°C