4a.7

[Jenna 1G]

Calculate the heat that must be supplied to a copper kettle of mass 400.0 g containing 300.0 g of water to raise its temperature from
20.0 °C to the boiling point of water, 100.0 °C. (b) What percentage of the heat is used to raise the temperature of the water? (See Table 4A.2.)
how would you set up this equation?

[Andrew Nguyen 1E]

Hi,

For this question, you have to consider the heat of the copper and heat of the water separately. First, you would calculate q for the copper kettle using the given mass and specific heat and change in temperature. Then, you would perform the same calculation for q for the water. This is because the copper and water have different specific heat values. The same delta T applies for both calculations since they are being heated concurrently. You would then add those two heat values to get the overall heat of the system.

[Kailin Mimaki 2K]

I approached this problem by using the equation q=m*c*deltaT. We need to raise the temperature of both water and the copper, so you would add the q value for water and copper together: (300)(4.18)(80)+(400)(0.38)(80). For part b, you take the q value you calculated for water and use that as a the numerator. The denominator is just your answer in part a and then multiply this fraction by 100 to get the percentage. Hope this helped!

[Sean Sanders 1E]

You would set this equation up by finding the amount of energy needed to heat each substance to 100 C from 20 C. The sum of these heats would be the total amount of heat needed to raise both from 20 C to 100 C.