M: 0913 22 00 66
E: Athensvn.edu@gmail.com
A: Trung Yên 10, Trung Hòa, Cầu Giấy, Hà Nội.
SPECIFIC LATENT HEAT
1. Specific Heat Capacity
Amount of Heat (J) required to change the state of 1 kg of a matter without changing its
temperature.
-
Symbol: L
-
Unit:
𝑱
𝒌𝒈
𝒐𝒓
𝑱
𝒈
Example:
Water is cooling, the graph beside shows that the temp.
of water falls until it starts to solidify (at 0oC – melting
point) and remain constant until it has all solidified.
-
During cooling (AB), Heat is emitted to
surrounding, the amount of heat energy is call
“Latent heat”
2. Latent Heat equation
Heat required to change state of m (kg) subtance:
heat given out (or received) = mass × specific latent heat
𝐼𝑛 𝑠𝑦𝑚𝑏𝑜𝑙𝑠:
𝑸= 𝒎×𝑳
For example: a 5 kg mass of ice of specific latent heat 340 J/kg need to change to
water at 0oC, the heat received Q , is
𝐐 = mxL
= 5 kg × 340 J/kg
= 1700 J
CHƯƠNG TRÌNH ĐÀO
TẠO
PHỔ THÔNG CẤP 1-2-3
CÁC NGÀY TRONG TUẦN
 Khoa học (tích hợp chương trình Lý-Hóa-Sinh tiếng Anh, tiếng Việt)
 Toán (tích hợp chương trình tiếng Việt, tiếng Anh)
 Tiếng Anh (học bổng ASEAN/ASTAR, luyện thi chứng chỉ Cambridge)
1
M: 0913 22 00 66
E: Athensvn.edu@gmail.com
A: Trung Yên 10, Trung Hòa, Cầu Giấy, Hà Nội.
 Practice exercises
1. a How much heat will change 10 g of ice at 0 ºC to water
at 0 ºC?
b
What
quantity
of
heat
must
be
removed
from
20
g
of
water at 0 ºC to change it to ice at 0 ºC?
2. a How much heat is needed to change 5 g of ice at 0 ºC to
water at 50 ºC?
b
If
freezing
a
freezer
point
cools
in
10
200
g
of
minutes,
water
how
from
much
20
heat
ºC
is
to
its
removed
per minute from the water?
3. How long will it take a 50 W heater to melt 100 g of ice at 0 ºC ?
(Known that 𝑃𝑜𝑤𝑒𝑟 = 𝐸𝑛𝑒𝑟𝑔𝑦 / 𝑡𝑖𝑚𝑒 𝑖𝑛𝑡𝑒𝑟𝑣𝑎𝑙 )
4. Some
small
aluminium
rivets
of
total
mass
170
g
and
at
100 ºC are emptied into a hole in a large block of ice at 0 ºC.
a What will be the fi nal temperature of the rivets?
b How much ice will melt?
5. The values in Table below are required.
a) How much heat is needed to change 20 g of ice at 0 ºC to steam at 100 ºC?
b) An aluminium can of mass 100 g contains 200 g of water. Both, initially at
15 ºC, are placed in a freezer at -5.0 ºC. Calculate the quantity of heat that
has to be removed from the water and the can for their temperatures to fall
to -5.0 ºC.
CHƯƠNG TRÌNH ĐÀO
TẠO
PHỔ THÔNG CẤP 1-2-3
CÁC NGÀY TRONG TUẦN
 Khoa học (tích hợp chương trình Lý-Hóa-Sinh tiếng Anh, tiếng Việt)
 Toán (tích hợp chương trình tiếng Việt, tiếng Anh)
 Tiếng Anh (học bổng ASEAN/ASTAR, luyện thi chứng chỉ Cambridge)
2