Calculating Temperature Change Using Q=mCsΔT

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This problem is designed to get you comfortable working with the equation given, and is good because it gets you to think of Q in terms of joules.

Given Problem: 25 grams of gold (Au) is initially at 27°C. It absorbs 2.35 kJ of heat. What is the final temperature of the gold? The specific heat for gold is 0.128 J/g•°C

1. To approach this problem, we must first look at the equations we’re using. The mcΔT equation is our best bet seeing as we have the mass, specific heat, and the amount of heat absorbed.

2. Before anything else, convert the kilojoules to joules. This is because the specific heat of gold is given in terms of joules. This gives us 2350 joules absorbed. This is our “q” value.

3. Now, we can plug everything into the mcΔT equation, and solve for the final temperature. Our mass is 25 grams, our specific heat is .128, and our initial temperature is 27 Celsius. For now, multiply the mass and specific heat together, but keep the temperature as it is.

4. Distribute the 3.2 value to the change in temperature equation. Now it’s just algebra! Solve for Tf by getting it on one side of the equation and dividing through. Don’t forget however, that when we add the 86.4 to the left hand side of the equation, we’re adding it to 2350 Joules.

5. Final Answer! 

I hope this makes sense. My brain’s a little fuzzy today, so feel free to check me on my numbers.

Questions? Feedback? Leave a comment!

Thanks guys!


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