Question

An unknown mass of each of the following substances, initially at 22.0 ∘C, absorbs 1970 J of heat. The final temperature is recorded as indicated. Find the mass of each substance.

a. Pyrex glass (Tf= 55.7 ∘C)

sand (Tf= 62.1 ∘C)

ethanol (Tf= 44.4 ∘C)

water (Tf= 32.2 ∘C)

Answer 1

Ti = 22

Q = 1970 J

Tf = 55.7 ; 62.1 ; 44.4 ;32.2

Cp pyrex = 0.75 J/gC

Cp sand = 0.830 J/gC

Cp ethanol = 2.46 J/gc

Cp water = 4.184 J/gc

then

Q = mC*(Tf-Ti)

m = Q/(C*(Tf-Ti))

then

a)

m = 1970/(C*(Tf-22))

m = 1970/(0.75*(55.7-22))

m = 77.94263 g of pyrex

b)

m = 1970/(C*(Tf-22))

m = 1970/(0.83*(62.1-22))

m = 59.18937g of sand

c)

m = 1970/(C*(Tf-22))

m = 1970/(2.46*(44.4-22))

m = 35.75 g of ethanol

d)

m = 1970/(C*(Tf-22))

m = 1970/(4.18*(32.2-22))

m = 46.20508 g of water