Chapter 6 Flashcards
In the laboratory a student finds that it takes 60.0 Joules to increase the temperature of 11.9 grams of solid zinc from 21.4 to 35.4 degrees celsius
The Specific Heat, s, of a substance is the energy required to raise the temperature of one gram of the substance by one degree.
Here is the data the student collected:
q = 60.0 Joules
m = 11.9 grams Zn
T2 = 35.4 °C
T1 = 21.4 °G|
Delta T = 14.0 °C|
The relationship she needs is:
q = s x m x deltaT
rearrange
s = q/mT
put in the values
60.0J/11.9g x 14.0C =57.2 °F 0.360J/gC
In the laboratory a student finds that it takes 259 Joules to increase the temperature of 14.6 grams of solid magnesium from 20.4 to 39.0 degrees Celsius.
The Specific Heat, s, of a substance is the energy required to raise the temperature of one gram of the substance by one degree.
Here is the data the student collected:
q = 259 Joules
m = 14.6 grams Mg
T2 =39.0 °C
T1 = 20.4 °C
Delta T = 18.6 °C
s = q/mT
s = 259J/14.6g x 18.6C =0.954J/gC
How much energy is required to raise the temperature of 10.4 grams of solid zinc from 21.3 °C to 36.4 °C?
Here is the information you are given:
= ?
m = 10.4 grams Zn
T2 =36.4 °C
T1 = 21.3 °C
Delta T = 15.1°
You must look up the specific heat of zine in the table linked in the References:
s = 0.388 J/g*C
q = s x m x T
q = 10.4g x 0.388 J/g*C x 15.1 *C =59.18 °F 60.9 J
What is the energy change when the temperature of 14.0 grams of solid magnesium is decreased from 35.4 °C to 22.6 °C?
q = ?
m = 14.0 grams Mg
T2 =22.6 °C
T1= 35.4 °C
Delta T = -12.8C
you must look up the specific heat of mg
s = 1.017J/g*C
q = s x m x T
q = 14.0g x 1.017 J/g*C x -12.8 *C =8.96 °F-182J
heat is removed in this case so q is negative
A sample of solid graphite is heated with an electrical coil if 142 joules of energy are added to a 11.9 gram sample initially at
23.0°C, what is the final temperature of the graphite?
q = 142 Joules
m = 11.9 grams C
T2 =?
T1= 23.0°C
delta T = ?
specific heat capacity of graphite
s = 0.711
q = s x m x T
T = q/sm
142J/11.9g x 0.711 J =16.8*C
solve for T2
16.8 + 23.0 =39.8*C
A sample of solid tungsten is heated with an electrical coil, if 29.7 Joules of energy are added to a 13.8 gram sample and the final temperature is 38.1°C, what is the initial temperature of the tungsten?
q = 29.7 Joules
m = 13.8 grams W
t2 = 38.1°C|
T1 = ?
Delta T = ?
Specific heat of tungsten
s = 0.133J/g*C
T = q/sm
29.7J/ 13.8g x 0.133J =0.0981 ft lb 16.2*C
Solve for T1
38.1 - 16.2 =21.9*C
The specific heat capacity of silver is 0.24 J°C-g
a. Calculate the energy required to raise the temperature of 142.0 g Ag from 274 K to 298 K
Energy =
b. Calculate the energy required to raise the temperature of 1.0 mole of Ag by 1.0°C (called the molar heat capacity of Silver).
Molar Heat Capacity =
c. It takes 1.20 kj of energy to heat a sample of pure silver from 12.8°C to 14.0°C. Calculate the mass of the sample of Silver.
Mass =
the heat of C of a substance is defined as
C = heat absorbed/ increase intemperate
a. specific heat capacity = 0.24J x 0.24 J since deltaT(K) = Delta T(*C)
Energy = s x m x T
0.24 x 142.0g x (298K - 274K) = 8.2x10^2J
b. molar mass heat capacity = 0.24J x 107.9g Ag = 26 mol
c. 1200 J =885.0746 ft lb 0.24 x m x (14.0C-12.8C)
m= 1200/0.24 x 1.2 =4.2x10^3
It takes 510. J to raise the temperature of 109.2 g of a liquid from 22.0’C to 59.0’C. What quantity of energy is required to the change the temperature of 10,1 g of the liquid from -17.0°C to
When an object changes temperature, the heat can be cakulated from the equation
9 = s x m x DeltaT
where s is the specific heat capacity, m is the mass, and A T is the change in temperature.
Using this equation, we can find the specific heat capacity of the liquid
s = q1/m1T1
s = 510.J/109.2g x (59.0 c - 222.0C) = 0.1262
now we can find the quantity of energy required
q2 = s x m2 x T2 =
q2 = 0.1262 x 10.10g (74.0C - (-17.0C)) = 116 J
