Calculating Energy and Molar Mass

The video tutorial covers different types of delta H problems, focusing on exothermic reactions where energy is released. It explains how to calculate the energy involved in reactions using moles, specifically for carbon and N2H4 reactions. Additionally, it discusses determining Delta H without a chemical equation by calculating Q and moles.

What does a negative Delta H indicate about a reaction?

• The reaction does not involve energy change.

• The reaction absorbs energy.

• The reaction is endothermic.

• The reaction is exothermic.

How many kilojoules of energy are released when 45 grams of carbon react?

• 31 kJ

• 45 kJ

• 12 kJ

• 24.8 kJ

What is the first step in calculating energy released from a given mass of a reactant?

• Convert grams to liters.

• Convert grams to moles.

• Convert moles to liters.

• Convert moles to grams.

How much energy is released when 25.4 grams of N2H4 react?

• 500 kJ

• 331.8 kJ

• 420 kJ

• 250 kJ

What is the relationship between Q of water and Q of the chemical reaction?

• They are unrelated.

• They are equal and both are positive.

• They are equal but have opposite signs.

• They are equal and have the same sign.

What is the specific heat of water used in the calculations?

• 5.184 J/g°C

• 4.184 J/g°C

• 3.184 J/g°C

• 6.184 J/g°C

How do you convert joules to kilojoules?

• Subtract 1000.

• Multiply by 1000.

• Divide by 1000.

• Add 1000.

What is the molar mass of CaCl2 used in the calculations?

• 100.984 g/mol

• 130.984 g/mol

• 110.984 g/mol

• 120.984 g/mol

What is the Delta H value calculated for the reaction involving CaCl2?

• -96.66 kJ/mol

• -86.66 kJ/mol

• -76.66 kJ/mol

• -106.66 kJ/mol

What is the final step in calculating Delta H for a reaction?

• Multiply Q by moles.

• Divide Q by moles.

• Subtract moles from Q.

• Add Q and moles.