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Calculation questions
Endothermic and Exothermic
Vocabulary
Hess's Law
Potpourri
100
How many Joules are in 146 calories
What is 611 Joules
100
A process that absorbs heat is called
What is endothermic
100

The study of the energy changes in chemical reactions.

What is thermochemistry?

100
If you add 2 or more thermochemical equations to give you a final equation, what does it allow you to do?
What is determine the heat of the reaction directly
100
What happens to the water in a calorimeter when an exothermic reaction occurs in it?
What is absorbs heat, and a rise in temperature.
200

What is the specific heat of a substance if 1560 calories is required to raise a 312 g sample by 15 degrees Celsius?

What is 0.33 cal/gºC

200
Which process is exothermic the vaporization of water/the freezing of water?
What is the freezing of water
200
The energy released or absorbed when a solid dissolves.
What is heat of solution
200

Using the following data, calculate the enthalpy change (ΔH) for the reaction:

C(graphite) + 2H₂(g) → C₂H₄(g)

Given:

  • • C₂H₄(g) + H₂(g) → C₂H₆(g), ΔH = -136 kJ
  • • C(graphite) + 2H₂(g) → C₂H₆(g), ΔH = -84 kJ

What is ΔH for the formation of C₂H₄(g)?

What is (delta)H=+52kJ

200
Why does warm water have a more rapid of evaporation than cold water?
What is Its molecules have a higher average kinetic energy.
300

How much energy does it take to convert 750 grams of ice at -15ºC to liquid water at 40ºC?

What is 399 kJ

300
What kind of equation is the following reaction: CH4 + O2 -> CO2 + H2O + 1725 kcal
What is exothermic
300
A quantity of heat needed to change 1 gram of water by 1 degree Celsius.
What is calorie
300

Calculate ΔH for the reaction:
CO(g) + 1/2 O₂(g) → CO₂(g)

Given:
• C(s) + O₂(g) → CO₂(g), ΔH = -393.5 kJ
• C(s) + 1/2 O₂(g) → CO(g), ΔH = -110.5 kJ

-283.0kJ

300
What is the formula to calculate the amount of heat energy exchanged between the system and its surroundings?
What is q= m c (delta)T
400

2 KCl + 3 O2 -> 2KClO3 Given that the heat of formation of potassium chloride is -436 kJ/mol and the heat of formation of potassium chlorate is -391 kJ/mol, determine the heats of reaction.

What is 90 kJ

400
What is an exothermic reaction?
What is a chemical reaction that releases energy
400

A change in which a system’s internal energy increases (thus energy is absorbed) also a positive delta H

What is endothermic?

400

Find (delta)H: H2SO4(l) -> SO3(g)+H20(g)

What is (delta)H=176.5kJ

400

If you were to touch a flask in which an endothermic reaction was occurring, the flask would feel _____ before the reaction started.

warmer

500

A certain mass of water was heated with 41,840 Joules, raising its temperature from 22.0ºC to 28.5ºC. Find the mass of water

What is 1538.46 g

500
What happens to the system in an endothermic process?
What is the system gains heat and the surroundings cool down
500

What does it mean if the (delta)H value for a chemical reaction is positive?

What is reactants have less potential energy than products.

500

Find (delta)H: N2H4(l)+CH4O(l) -> CH2O(g)+N2(g)+3H2(g)

What is (delta)H=79.4kJ

500

What determines the amount of temperature change due to a chemical reaction?

What is the amount of heat released or absorbed by the reaction