Thermochemistry

The diagram shows what happens when zinc reacts with hydrochloric acid. Which of these best describes the energy transformation that occurs during this reaction?

• Thermal energy - kinetic energy

• Kinetic energy -potential energy

• Chemical energy - thermal energy

• Potential energy - chemical energy

Tags

NGSS.HS-PS1-4

The potential energy diagram of a reaction is shown. Which statement below is correct relating to this reaction?

• #1 represents the enthalpy change for this exothermic reaction.

• #2 represents the enthalpy change for this endothermic reaction.

• #3 represents the enthalpy change for this endothermic reaction.

• #4 represents the enthalpy change for this exothermic reaction.

Tags

NGSS.HS-PS1-4

During an exothermic reaction, heat content in the surroundings increases because

• heat energy is destroyed during reactions

• the reaction absorbs heat energy

• the energy contained in the reactants is lower then the products

• the energy contained in the products is lower than the reactants

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

The diagram represents two solids and the temperature of each. What occurs when the two solids are placed in contact with each other?

• Heat energy flows from solid A to solid B. Solid A decreases in temperature

• Heat energy flows from solid A to solid B. Solid A increases in temperature

• Heat energy flows from solid B to solid A. Solid B decreases in temperature.

• Heat energy flows from solid B to solid A. Solid B increases in temperature.

Tags

NGSS.HS-PS3-4

When methane, CH4, and oxygen, O2, are mixed in a stove and ignited, a lovely blue flame results. The balanced equation is: CH₄(g) + 2O₂(g) 2H₂O(g) + CO₂(g) What can be said about the energy involved in this chemical reaction?

I. The average kinetic energy of the products is greater than that of the reactants.

II. The chemical energy stored in the reactants is greater than the chemical energy stored in the products.

III. Chemical energy in the reactants is changed into heat energy and light energy.

• I only

• II only

• III only

• I, II, and III

Tags

NGSS.HS-PS1-4

How do you calculate Enthalpy of a reaction?

• ΔH = ΔH_products - ΔH_reactants

• ΔT = q / mC

• ΔG = ΔH -TΔS

• E = mc²

Tags

NGSS.HS-PS1-4

Name the type of enthalpy for the following reaction:

Na⁺ (g) --> Na⁺ (aq) ΔH = -364 kJmol^-1

• Standard enthalpy of neutralisation, ΔH_neut^o

• Standard enthalpy of solution, ΔH_soln^o

• Standard enthalpy of hydration, ΔH_hyd^o

• lattice energy, ΔH_lattice^o

Tags

NGSS.HS-PS1-4

N₂ +  3H₂ −->  2NH₃ 
How many moles of ammonium are produced when 3 moles of nitrogen react with hydrogen?

• 6 moles Ammonium
• 1.5 moles ammonium
• 9 moles ammonium
• 9 moles hydrogen

Tags

NGSS.HS-PS1-7

C+ O₂ --> CO₂ + 60kJ, what is the value for ΔH for the reaction?

• +60
• -60
• there is no way to know

Tags

NGSS.HS-PS1-4

A reaction that gives out energy to the surroundings causes the surroundings ....

• temperature to drop

• temperature to rise

• temperature to remain constant

• temperature to vary

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4