Unit 7 Part 2 - Enthalpy & Hess's Law

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

NGSS.HS-PS3-1

H₂ + Cl₂ --> 2 HCl + 1845 kJ
Is this reaction endothermic or exothermic?

• Endothermic 
• Exothermic

Tags

NGSS.HS-PS1-4

Refer to the following question:
2N₂ + 3H₂ --> 2NH₃ + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?

• 92 kJ
• 0.143 kJ
• 23 kJ
• 15 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

During an endothermic reaction in a beaker if we are part of the surroundings and touched the beaker, it would feel _______.

• Warm

• Cold

• Bubbly

• Damp

Tags

NGSS.HS-PS3-4

(Hess's Law)Calculate the ∆H for the following reaction: 2H₂O₂ →  2H₂O  + 1 O₂ 
You are given these two equations:
2H₂  +  O₂ → 2H₂O            ∆H  =  -572 kJ
H₂  +  O₂  →  H₂O₂            ∆H  =  -188 kJ 

• ∆H  =  -948 kJ 
• ∆H  =  -196 kJ 
• ∆H  =  -384 kJ 
• ∆H  =  -188 kJ 

Tags

NGSS.HS-PS1-4

Calculate the enthalpy of reaction (ΔH).

4CO_{2 (g)} + 6H₂O _(g) → 2C₂H_{6 (g)} + 7O_{2 (g)}

ΔH_f^o [CO_2(g)] = -393.5 kJ

ΔH_f^o [H₂O_(g)] = -241.8 kJ

ΔH_f^o [C₂H_6(g)] = -84.7 kJ

• 550.647 KJ/mol

• 2855.584 KJ/mol

• -550.647 KJ/mol

• -2855.584 KJ/mol

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Enthalpy is energy absorbed or relased during a chemical reaction as

• light.
• heat.
• sound.
• pressure.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

When ammonium nitrate dissolves in water, the solution gets cold. Which is true?

• Reaction is ENDOTHERMIC with positive ΔH
• Reaction is ENDOTHERMIC with -ΔH
• Reaction is EXOTHERMIC with a -ΔH
• Reaction is EXOTHERMIC with +ΔH

Tags

NGSS.HS-PS1-4

What type of reaction occurs in a hand warmer

• exothermic
• endothermic

Tags

NGSS.HS-PS1-4

If a temperature of a reaction increases from 30-35 degrees, explain what happens.

• The reaction is endothermic
• The reaction is exothermic
• The reaction is photosynthetic
• the reaction is endothermic and exothermic

Tags

NGSS.HS-PS1-5