Cumulative Exam — Cumulative exam Answers

In an experiment, a student wants to increase the rate of a reaction that involves gases. Which change to the reactants would accomplish this?

The enthalpy of formation of water is –285.8 kJ/mol. What can be inferred from this statement?

Consider the reaction pathway graph below. Which indicates the energy that must be absorbed to initiate the reaction?

According to the collision theory, which is required for a high number of effective collisions?

Which is the first step in the dissolving process?

Which is the formula mass of Na2SO4?

Consider the unbalanced equation for the oxidation of aluminum._Al + _O2 _Al2O3Which sequence of coefficients should be placed in the blanks to balance this equation?

The expression below was formed by combining different gas laws. Which law was used to determine the relationship between the volume and the number of moles in this equation?

Why does the presence of lone pair electrons contribute to the polarity of a water molecule?

What is the percent by mass of magnesium sulfate in MgSO4 · 7H2O?Use .

The chemical equation below shows the burning of magnesium (Mg) with oxygen (O2) to form magnesium oxide (MgO).2Mg + O2 2MgOThe molar mass of O2 is 32.0 g/mol. What mass, in grams, of O2 is required to react completely with 4.00 mol of Mg?

Water is dissolved into n-butanol (a polar liquid). Which is the second step at the molecular level as water dissolves into n-butanol?

Which contributes to the dissolution of sugar in water?

A beam of light passes though a liquid in a test tube without scattering. Which type of mixture is most likely in the test tube?

The reaction of a Lewis acid with a Lewis base would most likely be accompanied by an increase in which item?

What is the true ratio of atoms in a molecule or formula unit called?

A gas in a rigid container at 25°C has a pressure of 0.96 atm. A change in temperature causes the pressure to increase to 1.25 atm. What is the new temperature of the gas?Use .

Which task most likely involves a calculation that uses moles?

A sample of propane (C3H8) has a mass of 0.47 g. The sample is burned in a bomb calorimeter that has a mass of 1.350 kg and a specific heat of 5.82 J/(g • °C). How much energy is released by the reaction if the temperature of the calorimeter rises by 2.87°C?Use .

The chemical equation below shows the combustion of methane (CH4).CH4 + 2O2 CO2 + 2H2OThe molar mass of oxygen gas (O2) is 32.00 g/mol. The molar mass of carbon dioxide (CO2) is 44.01 g/mol. What mass of CO2, in grams, will form when 8.94 g O2 completely react?