Extend your thinking: In addition to calculating specific heat capacities, some calorimeters can be used to determine how much energy is in food. The energy in food is usually expressed in calories or kilocalories (Calories). A calorie is the amount of energy needed to change the temperature of 1 g of water by 1 C. There are 1,000 calories in a Calorie.
A. How many joules are in 1 calorie? (The specific heat of water is 4.184 J/g °C.)
B. Suppose a snack bar is burned in a calorimeter and heats 2,000 g water by 20 °C. How much heat energy was released? (Hint: Use the specific heat equation.) Give your answer in both joules and calories.
C. How many kilocalories (Calories) does the snack bar contain?

A. 4.184.

B. 167360 cal or 700234.24 J.

C. 167.36.

A. You can just Google this one, but the conversion is 1 cal = 4.184 J.

B. Specific heat equation is q = mcΔT, m being mass, c being specific heat capacity, and ΔT being change in temperature.

We know that m = 2000 g, ΔT = 20 (because we are told that it heats the water by 20 °C), c = 4.184 (because we are calculating it for water).

So, q = 2000 · 4.184 · 20 = 167360.

C. This answer makes sense because when you divide it by 1000 to get the Calories (what we use in real life), you get 167.36 which seems normal for a snack bar.

Hope this helps.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).