Joule

Calorie

The heat content

The specific heat

A + B $$\rightarrow$$ C+ 50 kJ

A + B $$\rightarrow$$ C

$$\Delta H$$ = -50 kJ

A + B -50 kJ $$\rightarrow$$ C

A + B +50 kJ $$\rightarrow$$ C

The surrounding

The system

The system boundary

The universe

1 g of water

1 g of mercury

1 g of iron

1 g of aluminum

negative - exothermic

positive - exothermic

negative - endothermic

positive - endothermic

a

b

c

d

-550 kJ/mol

-124 kJ/mol

+486 kJ/mol

+5496 kJ/mol

-225 kJ/mol

-75 kJ/mol

+75 kJ/mol

+225 kJ/mol

+8.36 kJ/mol

-16.7 kJ/mol

-8.36 kJ/mol

+16.7 kJ/mol