Pleas HELP!!!!!! 1. Water\'s heat of fusion is 80. cal/g , and its specific heat
ID: 916088 • Letter: P
Question
Pleas HELP!!!!!!
1. Water's heat of fusion is 80. cal/g , and its specific heat is 1.0calgC . Some velomobile seats have been designed to hold ice packs inside their cushions. If you started a ride with ice packs that held 1300 g of frozen water at 0 C , and the temperature of the water at the end of the ride was 32 C , how many calories of heat energy were absorbed?
2. Water's heat of fusion is 80. cal/g , its specific heat is 1.0calgC, and its heat of vaporization is 540 cal/g . A canister is filled with 340 g of ice and 100. g of liquid water, both at 0 C . The canister is placed in an oven until all the H2O has boiled off and the canister is empty. How much energy in calories was absorbed?
3. High-pressure liquid chromatography (HPLC) is a method used in chemistry and biochemistry to purify chemical substances. The pressures used in this procedure range from around 500 kilopascals (500,000 Pa) to about 60,000 kPa (60,000,000 Pa). It is often convenient to know the pressure in torr. If an HPLC procedure is running at a pressure of 5.22×108 Pa , what is its running pressure in torr?
4. A sample of ideal gas is in a sealed container. The pressure of the gas is 655
torr , and the temperature is 24 C . If the temperature changes to 87 C with no change in volume or amount of gas, what is the new pressure, P2, of the gas inside the container?
5. Using the same sample of gas (
P1 = 655 torr , T1 = 24 C ), we wish to change the pressure to 6550 torr with no accompanying change in volume or amount of gas. What temperature T2, in Celsius, is needed to reach this pressure?
6. A sample of ideal gas at room temperature occupies a volume of 11.0 L at a pressure of 452 torr . If the pressure changes to 2260 torr , with no change in the temperature or moles of gas, what is the new volume, V2?
7. If the volume of the original sample in Part A (
P1 = 452 torr , V1 = 11.0 L ) changes to 66.0 L, without a change in the temperature or moles of gas molecules, what is the new pressure, P2
Explanation / Answer
1)
heat required to melt the ice = mass x heat of fusion
so
Q1 = 1300 x 80
Q1 = 104000 cal
noq
heat required to raise the temp of water at 0 C to 32 C = mx s x dT
so
Q2 = 1300 x 1 x 32
Q2 = 41600
so
total heat absorbed = 104000 + 41600
total heat absorbed = 145600
so
145.6 kcal of heat is absorbed
2)
Q1 = heat required to melt the ice
Q1 = 340 x 80
Q1 = 27200 cal
now
total mass of water = 340 + 100 = 440
now
heat required to raise the temperature to 100 C
Q2 = m x s x dT
Q2 = 440 x 1 x 100
Q2 = 44000 cal
now
heat required to vaporize
Q3 = 440 x 540
Q3 = 237600 cal
total heat = Q1 + Q2 + Q3
total heat = 27200 + 44000 + 237600
total heat = 308.8 k cal
so
308.8 kcal of energy is absorbed
3)
we know that
1 pa = 0.0075 torr
so
pressure = 5.22 x 10^8 x 0.0075
pressure = 3.915 x 10^6 torr
so
the pressure is 3.195 x 10^6 torr
4) PV = nRT
volume is constant
so
P1/T1 = P2 / T2
655 / 297 = P2 / 360
P2 = 793.94
so
new pressure is 793.94 torr
5)
volume = constant
so
P1 / T2 = P2 / T2
655 / 297 = 6550 / T2
T2 = 2970 K
T2 = 2970 - 273
T2 = 2697
so
the temp should be 2607 C
6)
P1V1 = P2V2
452 x 11 = 2260 x V2
V2 = 2.2
so
the new volume is 2.2 L
7)
P1V1 = p2 V2
452 x 11 = P2 x 66
P2 = 75.33
so
the new pressure is 75.33 torr