Download Practice Problems and Solutions for Quiz: 100g of water was

Practice Problems and Solutions for Quiz:
1. 100g of water was warmed 50 degrees C. Find the energy in Joules and
calories.
2. 50g of gold was warmed from 30 degrees C to 590 degrees C. If the specific
heat of gold is 0.129J/gC, how much energy was used to heat the gold?
3. A student took 40g of a metal at 5C and added it to 30g of water at 50C. The
final temp was 40C. Find the specific heat of the metal.
4. 80 g of aluminum with a specific heat of 0.9J/gC was at 75C was added to
70g of water at 10C. Find the final temperature.
Solutions
1. 100g of water was warmed 50 degrees C. Find the energy in Joules and
calories.
Q=gCpT
Q= (100g)(4.18J/gC)(50C)
Q=20,900J
20,900J x (1cal/4.18J) =5,000 cal
or
Q=(100g)(1cal/gC)(50C)=5,000 cal
2. 50g of gold was warmed from 30 degrees C to 590 degrees C. If the specific
heat of gold is 0.129J/gC, how much energy was used to heat the gold?
Q=gCpT
Q=(50g)( 0.129J/gC)(560C)= 3,612J
3. A student took 40g of a metal at 5C and added it to 30g of water at 50C. The
final temp was 40C. Find the specific heat of the metal.
gCpT= gCpT
Qmetal
= Qwater
(40g)(Cp)(35C)=(30g)(4.18J/gC)(10C)
Cp= (30x4.18x10)/(40x35) = 0.896J/gC
4. 80 g of aluminum with a specific heat of 0.9J/gC was at 75C was added to
70g of water at 10C. Find the final temperature.
gCpT= gCpT
(80g)(0.9J/gC)(75-x)=(70g)(4.18J/gC)(x-10)
5,400-72x = 292.6x-2,926
8326=364.6x
22.84C = x