Question

An unknown mass of each substance, initially at 25.0 ∘C, absorbs 1950 J of heat. The final temperature is recorded. Find the mass of each substance.

a) Pyrex glass (Tf = 55.3 degrees Celsius)

b) sand (Tf = 62.3 degrees Celsius)

c) ethanol (Tf = 44.3 degrees Celsius)

d) water (Tf = 32.1 degrees Celsius)

Answer 1

We know that dH= mCdt {where dH=heat, m= mass of the substance,

C=specific heat capacity(J/g-C), dt= change in temperature}

(a) Pyrex glass:

dt= 55.3-25= 30.3^oC , C=0.84

now dH=mCdt

=> 1950 = m x 0.84 x 30.3

=>m=76.6 g

(b) Sand:

dt= 62.3 - 25 = 37.3^oC , C=0.8

dH=mCdt

1950= m x 0.8 x 37.3

=>m= 65.34g

(c) Ethanol:

dt= 44.3-25 = 19.3^o C , C= 2.3

now dH=mCdt]

1950 = m x 2.3 x 19.3

=> m = 43.92g

(d) water:

dt= 32.1-25 = 7.1^oC ,C = 4.184

dH=mCdt

=>1950 = m x 4.184 x 7.1

=> m = 65.64g

Thank you. Hope this answer would help