Question

QUESTION 1

Calculate the heat energy required to raise the temperature of a cup of water (300 grams) from 25°C to 100°C. Express your answer in Joules. (Be careful with powers of 10)

A		9.43 x 10e4 J
B		22,500 J
C		2.25 x 10e4 J
D		94,275 x 10e4 J
E		80 J
F		335 J

  

QUESTION 2

Calculate the heat energy required to raise the temperature of 5 gallons of water from 50 F to 130 F. Express your answer in Btu.

A		3,320 J
B		400 x 10e3 Btu
C		3.32 x 10e3 Btu
D		20,870 Btu
E		400 Btu
F		1676 Btu

1 points   

QUESTION 3

You are measuring the heat capacity of an unknown substance. You add 700 Joules of heat energy to a 100 gram sample of this substance and the temperature increases from 20.5°C to 24°C. Calculate the heat capacity of this substance according to these measurements.

A		700 J/g °C
B		0.5 J/g °C
C		100 J/g °C
D		7.0 J/g °C
E		70,000 J/g °C
F		2.0 J/g °C

Answer 1

1)

heat energy required = m * S * delta T

heat energy required = 300 * 4.186 * (100 - 25)

heat energy required = 9.43 *10^4 J

the heat energy needed is A) 9.43 *10^4 J

2)

change in temperature , delta T = (130 - 50)

delta T = 80 F

delta T = 80/1.8 = 44.4 degree C

mass of water = 5 gallons = 18.92 kg

heat energy needed = 18.92 * 4186 * 44.4

heat energy needed = 3519960 J = 3320 Btu

the correct option is C) 3.32 *10^3 Btu

3)

Heat capacity = heat energy/(change in temperature * mass)

Heat capacity = 700/((24 - 20.5) * 100)

Heat capacity = 2 J/(gm.degree C)

the correct option is F)