what steps to use?

Question

And unknown sample is being evaluated in lab. What is the specific heat capacity of the compound if it requires 430.30 J to raise the temperature of 69.95 grams of the unknown from 15.2 °C to 27.5 °C.

Answer 1

We will use the equation Q = m*c*ΔT to solve this problem. Before we begin putting in numbers, let's review what the parts of this equation mean. Q refers to the amount of heat (in Joules) that is needed to raise the temperature. m is the symbol for mass and refers to the amount of the substance (in kilograms). c is the specific heat capacity of the compound. Δ is pronounced "delta" and is a Greek symbol that is used in math and science to mean "change". T refers to the temperature (in either Celsius or Kelvin); thus, ΔT means "the change in temperature". We determine the ΔT by using the equation ΔT = final temperature -- initial temperature.

Now let's start attaching numbers to these symbols. The problem tells us that the compound "requires 430.30 J". We know that Q is measured in Joules (J), so Q = 430.30 J. The problem also tells us that there are "69.95 grams of the unknown compound". The mass has the symbol m and is measured in grams (kg). We know that we have 69.95 g, and 1000 g = 1 kg. So 69.95 g is equivalent to .06995 kg, so m = 0.06995 kg. The problem asks us what the specific heat capacity of the compound is. We know that the symbol for the specific heat capacity is c. So c = what we want to find. The problem says that the compound was raised from 15.2 degrees Celsius to 27.5 degrees Celsius. Thus, the initial temperature of the compound was 15.2 Celsius, and the final temperature was 27.5 Celsius. Since ΔT = final temperature -- initial temperature, we find by doing 27.5 -- 15.2 = 12.3. So ΔT = 12.3 Celsius.

Now we can put the numbers in the equation Q = m*c*ΔT like this:

430.30 = .06995 * c *12.3

The calculator says .06995 * 12.3 = 0.860385, so we can replace .06995 * 12.3 with 0.860385 in the equation:

430.30 = .0860385 * c

To find c, we divide both sides by 0.860385, so:

c = 430.30 / 0.860385

The calculator says 430.30 / 0.860385 = 500.1

With the proper units for specific heat capacity, our answer is

c = 500.1 J/(C*kg)

Answer 2

Hello Secoya, you can use your specific heat formula to solve for the specific heat of the compound. The specific heat is the amount of heat energy required to raise one gram of a substance one degree.

Q = 

Delta T is your temperature change.

27.5C-15.2C=12.3 C=delta T

m is the mass of your sample. 69.95 grams

C is your heat capacity-

Q is the heat energy required to change the samples temperature (430.30J).

430.30J= (69.95 grams)*(12.3C)*C

C=(430.30J)/(69.95 g*12.3 C)=0.500 J/(g*C).