Thermo Review

As 120 g of hot milk cools in a mug, it transfers 20, 000 J of heat to the environment. What is the temperature change of the milk? The specific heat of milk is 2.6 J/g·°C. (Q=mcΔT)

• 64 °C

• 1.56 °C

• 640 °C

• cannot be determined

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

If 25 J are required to change the temperature of 5.0 g of substance A by 2.0°C, what is the specific heat of substance A?

• 250 J/g C

• 10 J/g C

• 63 J/g C

• 2.5 J/g C

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

Based on the information in the table above, which of the following expressions gives the approximate ΔH° for the reaction represented by the following balanced chemical equation?

• ΔH°rxn=[(0kJ/mol)+(−394kJ/mol)]−[(−826kJ/mol)+(−111kJ/mol)]

• ΔH°rxn=[2(0kJ/mol)+ 3(−394kJ/mol)]−[(−826kJ/mol)+ 3(−111kJ/mol)]

• ΔH°rxn=[(−826kJ/mol)+ 3(−111kJ/mol)]−[2(0kJ/mol)+ 3(−394kJ/mol)]

• ΔH°rxn=[(−826kJ/mol)+(−111kJ/mol)]−[(0kJ/mol)+(−394kJ/mol)]

Tags

NGSS.HS-PS1-4

Consider the following equations.

Mg_(s) + O_2(g) → MgO_(s) ∆H = –602 kJ

H_2(g) + O_2(g) → H₂O_(g) ∆H = –242 kJ

What is the ∆H value (in kJ) for the following reaction?

MgO_(s) + H_2(g) → Mg_(s) + H₂O_(g)

• -844

• -360

• +360

• +844

Tags

NGSS.HS-PS1-4

The enthalpies of combustion of C(s), H2(g) and C4H9OH(l) (in kJmol^-1) are as follows  
C(s) + O₂(g)   ->  CO₂(g)                                               ∆H=a
H₂(g) + ½O₂(g)   ->   H₂O(l)                                        ∆H=b
C₄H₉OH(l) + 6O₂(g)   ->   4CO₂(g) + 5H₂O(l)   ∆H=c
What is the enthalpy change for the reaction shown below?
  4C(g) + 5H₂(l) + ½O₂(g)   ->   C₄H₉OH(l)

• c – 4a – 5b

• 2a + 10b - c

• 4a + 5b - c

• 2a + 5b + c

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-4

The enthalpy of reactions for the synthesis two oxides of phosphorus are:

P_4(s) + 3O_2(g) → P₄O_6(s) ΔH_f = –1600 kJ mol^–1

P_4(s) + 5O_2(g) → P₄O_10(s) ΔH_f = –3000 kJ mol^–1

What is the enthalpy change, in kJ mol^–1, for the reaction below?

P₄O_6(s) + 2O_2(g) → P₄O_10(s)

• +4600

• +1400

• –1400

• –4600

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

What type of reaction is shown in the reaction pathway?

• endothermic reaction

• exothermic reaction

Tags

NGSS.HS-PS1-4

Which statement is true regarding ENDOTHERMIC reactions?

• Temperature change is positive and enthalpy change is positive

• Temperature change is positive and enthalpy change is negative

• Temperature change is negative and enthalpy change is positive

• Temperature change is negative and enthalpy change is negative

The enthalpy change is a negative (-) value, what side of the equation will the energy value be on.

• Reactants

• Products

Tags

NGSS.HS-PS1-4

Define Endothermic by picking the correct statements. (Choose 3)

• ΔH is positive

• Energy is taken in from the surroundings (temperature goes down).

• Energy is given out to the surroundings (temperature goes up).

• · Products have less energy than the reactants

• products have more energy than the reactants