Environmental chem. topic 3

Question 1

What’s the specific heat capacity of water?

Answer 1

4.19

Question 2

What’s the Q in Q=MCAT

Answer 2

the quantity of thermal energy in
joules (J)

Question 3

What’s the M in Q=MCAT

Answer 3

the mass of the substance in grams
(g)

Question 4

Whats the C in Q=MCAT

Answer 4

the specific heat capacity of the
substance in J/g*˚C

Question 5

What’s the AT in Q=MCAT

Answer 5

change in temperature in ˚C

Question 6

Heat of fusion phase change?

Answer 6

solid to liquid

Question 7

Heat of fusion is energy absorbed or realized?

Answer 7

Absorbed

Question 8

Heat of fusion the amount of water (Kj/mol)?

Answer 8

6.01

Question 9

heat of solidification is energy absorbed or released?

Answer 9

Released

Question 10

Heat of solidification the amount of water (Kj/mol)?

Answer 10

6.01

Question 11

Heat of vaporization is energy realsed or absorbed?

Answer 11

absorbed

Question 12

Heat of vaporization is energy the amount of water?

Answer 12

40.66

Question 13

In Q=HxN what’s Q?

Answer 13

= quantity of thermal energy added in kJ

Question 14

In Q=HxN what’s N?

Answer 14

the amount of the substance in mol

Question 15

How much thermal energy is required to increase the temperature of 500 g
of water from 20.0C to 80.0C? The specific heat capacity of water is 4.19 J/g·ºC.

Answer 15

125,700J

Question 16

When 200 g of an unknown substance absorbs 4.30 kJ of thermal energy, the
temperature of the substance changes from 30.0C to 80.0C. Determine the
experimental specific heat capacity of the unknown substance.

Answer 16

0.43j/g˚c

Question 17

How much thermal energy is needed to heat 100 g of water at 25.0ºC to 100.0ºC,
without a change in phase? The theoretical specific heat capacity of water is 4.19
J/g·ºC.

Answer 17

31425

Question 18

b) How much thermal energy is absorbed when 100 g of water at 100.0ºC evaporates
completely, without a change in temperature? The heat of vaporization of water is 40.7
kJ/mol and the molar mass of water is 18.02 g/mol.

Answer 18

225.5 kj

Question 19

c) Using your answers from part a) and b) of question 28, calculate the amount of thermal energy needed to heat 100 g of liquid water at 25.0ºC to water vapour at 100.0ºC. Assume that all the water evaporates.

Answer 19

1279.12 kj/mol