Question

A 228 g metal bar requires 5.20 kJ to change its temperature from 11.8°C to 90.2°C. What is the specific heat of the metal?

Answer 1

Same formula,
\[Q=m\cdot c\cdot\Delta T\]
But now, you need c,
\[c=\frac{Q}{m\cdot \cdot\Delta T}\]

Answer 2

I recommend you to use SI units, so put Q in Joules.

Answer 3

ok and how do you do significant figures

Answer 4

significant figures?

Answer 5

yes its something my teacher told us. it determines where you put the decimal

Answer 6

Ah, ok. You must use the following rule. Always put the minimum number of significan figures when operate with numbers.

For example, the number 9.28 has 3 significant figures. Then number 0.3 has one significant figure (left zeros not count). If I operate with them,
\[0.03\cdot9.28=0.2784\]
But I have only one signficant figure, so I must put,
\[0.3\]
as the final result.

Answer 7

A more detailed explanation can be found here for more general cases,
http://en.wikipedia.org/wiki/Significant_figures

Answer 8

so what do you base the number of sigfigs in the equation on

Answer 9

like what would be the answer using sigfigs for A 228 g metal bar requires 5.20 kJ to change its temperature from 11.8°C to 90.2°C. What is the specific heat of the metal?

Answer 10

All numbers you use has three digits, so it must be three significant figures.

Answer 11

\[5.20/(228\cdot78.4)=2.91\cdot10^{-4}\ kJ/(g\cdot K)=2.91\cdot10^{-1}\ J/(g\cdot K)\]