Understanding Standard States and Enthalpy Changes

What analogy is used to explain standard states and enthalpy changes?

• A river flowing downstream

• A car accelerating

• A mountain altitude

• A tree growing taller

What is the standard state of a gas defined as?

• A pure sample at 0°C

• A pure sample at 2 atmospheres

• A pure sample at 100°C

• A pure sample at 1 atmosphere

How is the standard state of a liquid or solid defined?

• In its most stable form at 100°C

• In its most stable form at 50°C

• In its most stable form at 0°C

• In its most stable form at 25°C

What does the standard enthalpy change for a reaction involve?

• Reactants and products in any state

• Reactants and products in their standard states

• Only reactants in their standard states

• Only products in their standard states

What is the standard enthalpy of formation for a pure element in its standard state?

• Always positive

• Depends on the element

• Always negative

• Always zero

What is the standard enthalpy of formation for a compound?

• The enthalpy change when the compound is heated to 100°C

• The enthalpy change when the compound is dissolved in water

• The enthalpy change when two moles of the compound are formed

• The enthalpy change when one mole of the compound is formed from its elements in their standard states

What is the most stable form of carbon used in the example of propane formation?

• Carbon dioxide

• Charcoal

• Graphite

• Diamond

How many moles of hydrogen are needed to form propane in the example?

• 2 moles

• 8 moles

• 4 moles

• 6 moles

What is the standard enthalpy of formation for propane?

• 150.0 KJ per mole

• 103.8 KJ per mole

• 50.0 KJ per mole

• 75.5 KJ per mole

What tool can be used to predict if a reaction is endothermic or exothermic without conducting the experiment?

• A pH meter

• Tabulated standard enthalpies of formation

• A calorimeter

• A thermometer