Question

How much energy does it take to boil water for pasta? For a one-pound box of pasta

you would need four quarts of water, which requires 15.8 kJ of energy for every degree Celsius (°C) of temperature increase. Your thermometer measures the starting
temperature as 48°F. Water boils at 212°F.


a. [1 pts] How many degrees Fahrenheit (°F) must you raise the temperature?
b. [2 pts] How many degrees Celsius (°C) must you raise the temperature?
c. [2 pts] How much energy is required to heat the four quarts of water from
48°F to 212°F (boiling)?

Answer 1

a. 164°F

b.
`91.\overline 1 \ ^(\circ) C`

c.
`140.\overline 4` kJ

Step-by-step explanation:

The starting temperature of the water, T₁ = 48F

The temperature at which the water boils, T₂ = 212°F

a. The difference between the initial and the boiling water temperature, ΔT = T₂ - T₁

Therefore;

ΔT = 212°F - 48°F = 164°F

The temperature by which he temperature must be raised, ΔT = 164°F

b. 48°F = ((48 - 32)×5/9)°C = (80/9)°C =
`8.\overline 8 \ ^(\circ) C`

212°F = ((212 - 32)×5/9)°C = 100°C

∴ ΔT = 100°C -
`8.\overline 8 \ ^(\circ) C` =
`9.\overline 1 \ ^(\circ) C`

c. The heat capacity of the water = The heat required to increase four quartz of water by 1 °C = 15.8 kJ

∴ The heat required to raise four quartz of water by
`9.\overline 1 \ ^(\circ) C`, ΔQ = 15.8 kJ/°C ×
`9.\overline 1 \ ^(\circ) C` =
`140.\overline 4` kJ.