I do not know how to do question number 4. Help me, please!

Question

3) A 15.0 g sample of iron metal is heated from an initial temperature of 26.8°C to a final temperature of 112.3°C. The specific heat capacity iron is 0.450 J/g°C. How much heat is absorbed by the iron?

4) The same sample of iron described in Question 3 loses 84.0 joules of heat to the environment. If the initial temperature is 112.3°C, what is the final temperature?

Answer 1

(4) Specific heat capacity is 0.450 J / g °C

So as there are 15 g of iron this means you need 0.450 x 15 = 6.75 J of energy to increase the temperature by 1°C. In the same way for every 6.75 J of energy the iron loses, the temperature will fall by 1°C

So if it loses 84 J, temperature will fall by 84 / 6.75 = 12.4 ° C, so the final temperature will be 112.3 - 12.4 = 99.9 ° C.

Mike

Answer 2

Hey Lan,

1. To answer your first question, we need to use the formula q=mcΔT, where q= heat, m is mass (g), c is specific heat (J/g°C), and ΔT is the change in temperature.

To solve, we can just plug and chug,

q=mcΔT

q= (15.0g)(0.450J/g°C)(85.5°C)

q= 577.13J (rounding to 3 significant figures would be 577.J)

2. This part is just the reverse of the first portion.

To solve,

q=mcΔT

ΔT= q/(mc)

ΔT= (-84.0J)/(15.0g * 0.450J/g°C)

ΔT= -12.44°C

Now that we have the change in temperature, we can find the final temperature. The relationship between ΔT and the final and initial temperatures is as follows:

ΔT= T_final-T_initial

-12.44°C = T_final - 112.3°C

T_final= 99.9°C

Hope this helps!