The Specific Heat of Water

Specific Heat: The heat required to raise 1 g 1 g of water11ooC.

•The specific heat of water is 4.18 joules of heat per gram of water.

•We write: 4.18 J/goC

How much energy is required to change 220g of water

1.0oC?

• It would take 4.18 joules for every gram.

• It would take (4.18)(220) = 920 J• It would take 920J of energy.

How much energy is required to change 1.0g of water by

25.0oC?• It would take 4.18 joules for every

1.0oC.• It would take (4.18)(25.0) = 105 J• It would take 105J of energy.

How much energy is required to change 220.0g of water by 25oC?

• It would take 4.18 joules for every 1.0g changing by 1.0oC.

• It would take (220.0)(4.18)(25) = 23045 J

• It would take 23000J of energy.

Therefore, the formula for specific heat of water is…

Q = mctQ = heat required (J)M = mass of the water (g)C = specific heat of water (J/goC)

T = temperature (oC)

Q = mctWhat mass of water absorbs 3050J of heat energy when it is heated from 10.0oC to 30.0oC?

Q = 3050JC = 4.18J/goCt = 20.0oC

3050=m(4.18)(20.0)

3050=m(83.6)

Cancel the 83.6 so the m will be alone. Do this by doing the opposite operation. Divide by 83.6

3050=m(83.6)

83.6 83.6

36.5 = m

The mass is 36.5g

All substances have a specific heat.

Specific Heat (g/JoC)Aluminum Copper GoldLead Silver

0.9000.3860.126 0.128 0.233

Zinc Mercury AlcoholGraniteGlass

0.387 0.1402.400.7900.840

How much heat is needed to raise the temperature of 10.0g of gold

by 5.0oC? Q = ? J

m = 10.0 g

c = 0.126 J/goC

t = 5.0oC

Q = mct =(10.0)(0.126)(5.0)

= 6.3 J of heat is needed to raise the temperature of 10.0g of gold by 5.0oC.