NCFE Review 2C

A water sample was found to have a pH of 6 at 25°C. What is the hydroxide concentration in the water sample?

• 1x10^-8 M

• 6x10^-8 M

• 1x10^-6 M

• 6x10^-6 M

What is the pH of a solution of KOH with a hydroxide concentration of [OH] = 1x10^-4 M

• -10

• -4

• 4

• 10

In a titration experiment, if 30.0 mL of an HCl solution reacts with 24.6 mL of a 0.50-M NaOH solution, what is the concentration of the HCl solution?

• 0.41 M

• 0.61 M

• 1.5 M

• 370 M

Consider this reaction:

3Ca (s) + 2H₃PO₄ (aq) → Ca₃(PO₄)₂ (s) + 3H₂ (g)

How many moles of calcium are required to produce 60.0 g of calcium phosphate?

• 0.145 mole

• 0.194 mole

• 0.387 mole

• 0.581 mole

According to the equation 2H₂O (l) → 2H₂ (g) + O₂ (g), what mass of H₂O is required to yield 22.4 L of O₂ at STP?

• 12 g

• 18 g

• 24 g

• 36 g

Metallic sodium reacts violently with water to form hydrogen and sodium hydroxide according to the balanced equation:

2Na + 2H₂O → 2NaOH + H₂

How many moles of hydrogen gas are generated when 4.0 moles of sodium react with excess water?

• 1.0 mol

• 2.0 moles

• 3.0 moles

• 4.0 moles

What is the molarity of a solution containing 20.0 g of sodium hydroxide dissolved in 1.00 L of solution?

• 0.500 M

• 0.400 M

• 0.300 M

• 0.200 M

Tags

NGSS.HS-PS1-5

Consider this balanced chemical equation:

2H₂O₂ (aq) → 2H₂O (l) + O₂ (g)

Which will increase the rate of the reaction?

• increasing pressure on the reaction

• decreasing concentration of the reactants

• adding a catalyst to the reaction

• decreasing the temperature of the reaction

Tags

NGSS.HS-PS1-5

For the reaction

A⁺ (aq) + B^- (aq) → AB (s)

increasing the temperature increases the rate of the reaction. Which is the best explanation for this happening?

• The pressure increases, which in turn increases the production of products.

• The concentration of reactants increases with an increase in temperature.

• The average kinetic energy increases, so the likelihood of more effective collisions between ions increases.

• Systems are more stable at high temperatures.

Which statement explains why the speed of some reactions is increased when the surface area of one or all the reactants is increased?

• increasing surface area changes the electronegativity of the reactant particles

• increasing surface area changes the concentration of the reactant particles

• increasing surface area changes the conductivity of reactant particles

• increasing surface area enables more reactant particles to collide