Enthalpy definitions

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.

• The enthalpy of neutralisation

• The enthalpy of combustion

• The enthalpy of formation

• The enthalpy of reaction

What do we mean by the term standard conditions

• 1atm, 20C and 1moldm³

• 1atm, 0K and 1moldm³

• 10atm, 273K and 10mol/dm³

• 100kPa, 298K and 1mol/dm³

Tags

NGSS.HS-PS1-5

Define the term Exothermic by picking the correct statements

• Products have less energy than the reactants

• ΔH is negative

• ΔH is positive

• Energy is given out to the surroundings (temperature goes up).

• products have more energy than the reactants

Tags

NGSS.HS-PS1-4

Define Endothermic by picking the correct statements

• ΔH is positive

• Energy is taken in from the surroundings (temperature goes down).

• Energy is given out to the surroundings (temperature goes up).

• · Products have less energy than the reactants

• products have more energy than the reactants

Tags

NGSS.HS-PS1-4

ΔH value in an endothermic reaction is a positive number.

• True
• False

Tags

NGSS.HS-PS1-4

 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

• 4 only
• 1 only
• 3 and 4 only
• 2 and 3 only

Tags

NGSS.HS-PS1-4

What type of reaction is shown in the reaction pathway?

• endothermic reaction
• exothermic reaction

Tags

NGSS.HS-PS1-4

What type of reaction is shown in the reaction pathway?

• endothermic reaction
• exothermic reaction

Tags

NGSS.HS-PS1-4

The SI unit of heat and energy is the __________.

• calorie
• heat
• joule
• watt

Tags

NGSS.HS-PS3-4

Define standard enthalpy of combustion.

• Heat released when one mole of substance is burnt completely in excess oxygen.

• Heat absorbed when one mole of substance is burnt completely in excess oxygen under standard state.

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

• Heat change when one mole of substance is burnt partially in excess oxygen under standard state.