Stoichiometry and Heat

evaporation of water from your skin

• Exothermic reaction

• Endothermic reaction

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Calculate the number of kJ required for the reaction shown below, if you begin with 45.0 grams of water (H2O), and the ΔHrxn = +571.6 kJ. 2 H2O(l) → 2 H2(g) + O2(g)

• 714 kJ

• 729 kJ

• 747 kJ

• 800 kJ

Tags

NGSS.HS-PS3-1

Calculate the number of kJ required for the reaction shown below, if you begin with 48 grams of oxygen (O2) and the ΔHrxn = +180 kJ. N2(g) + 2 O2(g) → 2 NO2(g)

• 1.4 × 10² kJ

• 2.4 × 10² kJ

• 3.4 × 10² kJ

• 0.4 × 10² kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Calculate the change in energy (in kJ) for the reaction shown below, if you begin with 52 grams of fluorine (F2), and the ΔHrxn = −542 kJ. H2(g) + F2(g) → 2 HF(g)

• −7.4 × 10² kJ

• −3.4 × 10² kJ

• −6.4 × 10² kJ

• −5.4 × 10² kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Calculate the change in energy (in kJ) for the reaction shown below, if you begin with 75.0 grams of oxygen (O2), and the ΔHrxn = −902.0 kJ. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g)

• −423 kJ

• −413 kJ

• −513 kJ

• −523 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

PCl5(g) + 67 kJ → PCl3(g) + Cl2(g)

• Exothermic reaction

• Endothermic reaction

Tags

NGSS.HS-PS1-4

dissolving NH4Cl in water to make a cold pack

• Exothermic reaction

• Endothermic reaction

Tags

NGSS.HS-PS1-4

Is burning a candle exothermic or endothermic?

• Exothermic reaction
• Endothermic reaction

Tags

NGSS.HS-PS1-4

The enthalpy of a reaction is the negative of the enthalpy of the reverse reaction.

• Yes
• no

Calculate the change in energy (in kJ) for the reaction shown below, if you begin with 12 grams of hydrogen (H2), and the ΔHrxn = −572 kJ. 2 H2(g) + O2(g) → 2 H2O(g)

• −1.7 × 10³ kJ

• −6.7 × 10³ kJ

• −4.7 × 10³ kJ

• −0.7 × 10³ kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1