Question

How much heat is released when 40.0 g of ethanol cools from −120 °C to −136 °C?a.640 J

b.580 J
c 320 J
d.290 J

Answer 1

Hello there! Your answer is A. 640 J

You can get this by subtracting the temperatures (-136-120= -256.) Then, you divide this answer by 40.0 g to get 6.4.

Answer 2

Answer: a. 640 J

Explanation:

`Q= m* c* \Delta T`

Q= heat gained or released

m= mass of the substance = 40 g

c = heat capacity of solid ethanol= 1.0 J/g ° C

`\Delta T={\text{Change in temperature}}=(-136-(-120)^oC=-16^0C`

`Q=40g* 1.0J/g^oC* -16^oC`

`Q=-640J`

Thus heat released when 40.0 g of ethanol cools from −120 °C to −136°C is 640 Joules.