Answer to Question #169627 in General Chemistry for Samantha Hernandez

Question

A pyrex glass flask is filled with 200 g of water. The energy required to heat the system (the flask and the water) from 20 °C to 45 °C is 23.1 kJ. Assume that the specific heat capacity of water is 4.18 J g^–1 °C^–1. What is the heat capacity of the flask?

•  A. 36 J °C^–1
•  B. 88 J °C^–1
•  C. 76 J °C^–1
•  D. 60 J °C^–1
•  E. 2200 J °C^–1

Answer 1

mass of water, m=200g

H= 23.1Kj

T1= 20°C

T2= 45°C

C of water = 4.18J/g°C

But the mass of the glass was not given in the question, so let us assume that the combined mass of the glass and the water is the 200g given.

C of glass C_g= ?

H= m(T2-T1)(C_w + C_g)

23100= 200(45-20)(4.18+C_g)

23100= 5000(4.18+ C_g)

23100 = 5000C_g + 20900

23100-20900= 5000C_g

C_g= 2200/5000 = 0.44J/g°C

Unless the mass of the pyrex glass is given, there is no other alternative way of solving this question