Enthalpy definitions

Front

Match the definition below to the correct term. The enthalpy change that takes place when one mole of a compound is formed from its elements in their standard states under standard conditions.

Back

The enthalpy of formation

Front

What do we mean by the term standard conditions?

Back

100kPa, 298K and 1mol/dm³

Front

ΔH value in an endothermic reaction is a positive number.

Back

True

Front

For which of these processes is the value of ΔH expected to be positive?
1.  The temperature increases when calcium chloride dissolves in water.
2.  Steam condenses to liquid water
3.  Water boils
4.  Dry ice sublimates

Back

3 and 4 only

Front

What type of reaction is shown in the reaction pathway?

Back

exothermic reaction

Front

What type of reaction is shown in the reaction pathway?

Back

exothermic reaction

Front

The SI unit of heat and energy is the __________.

Back

joule

Front

Define standard enthalpy of combustion.

Back

Heat released when one mole of substance is burnt completely in excess oxygen under standard conditions with all substances being in their standard states.

Front

Enthalpy

Back

Energy stored in the chemical bonds in a substance

Front

What is true about endothermic reactions?

Back

Temperature change is negative and enthalpy change is positive.