General Chemistry Answers

If the actual yield during the experiment is 94g of P₂O₅, what is the percent yield of the reaction?

You are task to collect gases such as N2, O2, CO2, AND Ar gas. The partial pressure of the gases are 515 torr, 215 torr, and 98 torr respectively. What is the partial pressure of Ar, if the total pressure is 715 torr.

A certain reaction has TriangleH(degree symbol) = -73.80 kJ and TriangleS(degree symbol) = 0.00 J/K

A) Is this reaction is exothermic

B) Does this reaction lead to a decrease, an increase, or no change in the degree of disorder in the system? _______

C) Calculate triangleG(degree symbol) for this reaction at 298 K. If this value is less than 1 kJ/mol than enter O in the answer box.

TriangleG(degree symbol) = _____ kJ

D) Under the standard conditions at 298 K, this reaction is spontaneous.

A) In a chemical reaction 2 moles of solid decomposes to form one mole of gas. Would you expect TriangleS to be positive, negative, or close to zero for this reaction?

• TriangleS for this reaction should be positive.

1) In which of the processes described below should the entropy increase? Choose all of the correct possibilities.

a) ice cubes melting at -5 degrees Celsius and 1 atm pressure

b) water disappearing from a tea kettle by boiling away

c) gas sprayed onto a cold surface deposits (solidifies) and becomes part of the surface

d) dissolution of sugar in a hot cup of coffee

e) some dry ice left on a tabletop disappearing via sublimation

Calculate the standard enthalpy of formation of gaseous carbon dioxide (CO2) using the following thermochemical information:

2 Ca(s) + O2(g) <- -> 2 CaO(s) TriangleH=-1270.2 kJ

CaO(s) + CO2(g) <- -> CaCO3(s) TriangleH=-178.3 kJ

2 C(s) + 2 Ca(s) + 3 O2(g) <- -> 2 CaCO3(s) TriangleH=-2413.8 kJ

1) TriangleH= ____ kJ

Consider the following data.

Mg(s) + S(s) <— —> MgS(s). TriangleH=-598.0 kJ

SO2(g) <— —> S(s) + O2(g) TriangleH= +296.8 kJ

3 Mg(s) + SO2(g) <— —> MgS(s) + 2 MgO(s) TriangleH = -1504.6 kJ

Use Hess’s law to calculate TriangleH for the reaction below.

2 Mg(s) + O2(g) <— —> 2 MgO(s)

1) TriangleH = ____ kJ

When a 7.35 -g sample of solid iron(II) chloride dissolved in 36.0 g of water in a coffee-cup calorimeter the temperature rises from 21.00 degrees Celsius to 46.75 degrees Celsius. Calculate triangleH in kJ/mol FeCl2 for the solution process.

FeCl2(s) —> Fe^2+ (aq) + 2 Cl^- (aq)

The specific heat of water is 4.18 J/g-K.

1) TriangleH solution = ____ kJ/mol FeCl2.

At 1261 degrees Celsius the equilibrium constant for the reaction: 2 IBr(g) —><— I2(g) + Br2(g)

is Kp= 1.09. If the initial pressure of IBr is 0.00985 atm, what are the equilibrium partial pressures of IBr, I2, and Br2?

1) p(IBr) = ___

2) p(I2) = ____

3) p(Br2) = ____

Consider the following reaction. CH3OH(g) -> CO(g) + 2 H2(g). TriangleH = + 90.7kJ

The reaction is endothermic.

1) Calculate triangleE when 885.0 g of CH3OH(g) completely reacts at a constant temperature of 300 K and constant pressure of 0.95 atm. R= 8.314 J/mol*K and R= 0.08206 atm*L/mol*K _______ kJ

calculate mass of C from mass of CO2