Question

Find the amount of heat required to convert 10g of water at 100 degree Celsius into steam (specific layers heat of vaporisation of water=540cal/g)

Answer 1

Explanation:

10g of ice at -10℃ ⟶ steam at 100℃

↓Q

1

10g of ice 0℃

↓Q

2

↑Q

4

10g water 0℃ ⟶Q

3

10g water 100℃

First we need to bring the ice at -10℃ to 0℃.

△T = 10

m = 2g

S = 1cal/g/℃

Q

11

= ms△T

⇒ = 10 cal.

Then, we convert this ice into water Lfusion = 80cal/g.

Q

12

= mLfusion

⇒ = 2×80

⇒ = 160cal

Then we can increase the temp. of this water to 100℃

△T = 100-0

⇒ = 100

Q

13

= ms△T

⇒ = 2×100×1

⇒ = 200cal.

Now, we convert this water into steam.

Lvap = 540cal.

Q

14

= mLvap

⇒ = 2×540

⇒ = 1080cal

Heat required = Q

11

+Q

12

+Q

13

+Q

14

⇒ = 10 +160+200+1080

⇒ = 1450cal.