Written Work 3 : 1st Law of Thermodynamics

The 1st law of Thermodynamics states that the

• Energy can not be created or destroyed. It just changes forms.

• Energy can only be created by the sun

• Some energy is lost to the environment.

1200 J of heat are added to a sample of gas while 400 J of work is done by the gas. What is the change in internal energy of the gas?

• 800 J

• 1600 J

• -800 J

• -1600 J

What does the "U" stand for the formula ∆U = Q + W

• Heat
• Temperature
• Work
• Internal energy

Which of the following energy transformations occur when a lamp that is plugged into a wall socket is functioning correctly?

• Chemical → light

• Electrical → chemical

• Electrical → light

• Chemical → electrical

The SI unit of heat and energy is the __________.

• calorie
• heat
• joule
• watt

Tags

NGSS.HS-PS3-4

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

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

Which statement is true regarding endothermic reactions?

• a) Temperature change is positive and enthalpy change is positive
• b) Temperature change is positive and enthalpy change is negative
• c) Temperature change is negative and enthalpy change is positive
• d) Temperature change is negative and enthalpy change is negative

Tags

NGSS.HS-PS1-4

How many Joules in 5 calories ?

• 4.19 J

• 8.38 J

• 20. 95 J