6 Formulas

PS 6 Formulas

1 Food cal =1 Cal =1 Kilocalorie=1000 calories

1 Cal = 4.18 kJ = 4180 J  and 1 cal = 4.18 J

Ex.  Convert the following to:

Joules                                                          calories

140 Kj=                                                       4180 joules=

50 calories=                                 7 Calories=

10 Calories=                        4 Kcal=

Joules

140 Kj=                   140 X 1000=140,000 J                              

200 calories=   200X 4.18  = 836 J            

10 Calories= 10 X 1000X 4.18= 41,800 J

calories      

4180 joules= 4180/4.18 =1000 cal

7 Calories= 7 X 1000 =7,000 cal

4 Kcal= 4 X 1000 =4,000 cal

Helpful hints*

Joules are always larger than calories!

The numbers you need to know are 1000 and 4.18!

calories to joules multiply by 4.18

Joules to calories divide by 4.18

Again think 1000 when you see Kilo!

Food calorie and big C Calorie think Kilo!!!!

*Heat capacity =

The amount of energy it takes to change an objects temperature exactly 1 o C.

Specific heat capacity =Specific Heat = C =

The amount of heat it takes to raise 1 g of a substance 1 o C.  It is usually measured in J/g C

Example

What is the amount of energy needed to raise 10 g of Magnesium 2 o C?

Δ=Change

Mass(Specific Heat)(Δ of T)= Energy

10 g(1.01 J/g o C) 2 o C =20.2 J