Enthalpy

ΔH value in an endothermic reaction is a positive number.

• True
• False

Tags

NGSS.HS-PS1-4

 For which of these processes is the value of ΔH expected to be positive?
1.  The temperature increases when calcium chloride dissolves in water.
2.  Steam condenses to liquid water
3.  Water boils
4.  Dry ice sublimates

• 4 only
• 1 only
• 3 and 4 only
• 2 and 3 only

Tags

NGSS.HS-PS1-4

What type of reaction is shown in the reaction pathway?

• endothermic reaction
• exothermic reaction

Tags

NGSS.HS-PS1-4

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

Which of the following has a ΔH_f^o value of 0?

• Br₂(g)

• N(g)

• CO(g)

• Ne(g)

Tags

NGSS.HS-PS1-4

Endothermic reactions feel

• warm
• cold

Tags

NGSS.HS-PS1-4

Describe the energy change that takes place when bonds are broken. 

• a) Energy is given out 
• b) Energy is taken in 
• c) Energy is taken in and then given out 
• d) Energy is given out and then taken in

Tags

NGSS.HS-PS1-4

What does the circle mean in ΔH°?

• Standard Conditions (T=298.15 K P=1 atm)

• Standard Temperature and Pressure (T=273.15 K P=1 atm)

• Degree K

• Degree C

• endothermic reaction

• exothermic reaction

• reaction with catalyst

• equilibrium reaction

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Calculate the change in Enthalpy of the combustion reaction of liquid Ethanol (C₂H₅OH). When Ethanol has an enthalpy of -286 kJ/mol, water is liquid and oxygen and carbon dioxide are in gas state.

• -286 kJ/ mol

• 1366 kJ/mol

• -2732 kJ/ mol

• -1366 kJ/mol