A backpacker collects snow at 0°C, and places it in a cooking pot on a camp stove. It takes 643 kJ of heat energy to melt the snow and bring the water to boiling. Assuming no heat loss, and neglecting the specific heat capacity of the pot, calculate the mass of snow that the backpacker collected. (Data: specific heat capacity of liquid water, c = 4.18 J/g⋅K; and: H2O(s) → H2O(l) ΔH = ΔHfusion = 6.02 kJ/mol)

mass (m) of the snow that the backpacker collected= 0.855 kg

Explanation:

Given that:

Q = 643 kJ = 643000 J

ΔHfusion = 6.02 kJ/mol = 6020 J/mol

number of mole of water H2O =

c = 4.18 J/g⋅K

ΔT = 100 K

Since there is a phase change from solid to liquid; then :

ΔH =

However without the given mass; we substitute for the number of moles; so:

Q =

m = 855 g

m = 0.855 kg

mass (m) of the snow that the backpacker collected= 0.855 kg

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.