Rates of Reaction

In the following reaction, the rate of formation for HI is 4.2 mL/s (cm³ s^-1). What is the rate of consumption of H₂ if the pressure and temperature remain constant? H₂(g) + I₂(g) → 2HI(g)

• -4.2 mL/s (cm³ s^-1)

• -8.4 mL/s (cm³ s^-1)

• -2.1 mL/s (cm³ s^-1)

• You cannot calculate with the given information.

Tags

NGSS.HS-PS1-7

Which is not a unit for measuring a rate of reaction?

• g/s

• L/min

• mol / (L x s)

• L / mol

Tags

NGSS.HS-PS1-5

Which experimental methods could be used to observe the progress of the following reaction? Cr₂O₇^2-(aq) + 6I^-(aq) + 14H⁺(aq) → 2Cr³⁺(aq) + 3I₂(aq) + 7H₂O(l) I. Change in colour II. Change in mass III. Change in electrical conductivity

• I and II

• I and III

• II and III

• I, II and III

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g) Which methods can be used to monitor the progress of the reaction? I. Change in colour of this reaction mixture II. Change in mass of this reaction mixture III. Change in volume of gas evolved

• I and II only

• I and III only

• II and III only

• I, II and III

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-7

100 cm³ of 10% hydrogen peroxide solution decomposes at 298 K to form water and oxygen. H₂O₂ (aq) → H₂O(l) + ½O₂(g) The dotted line graph represents the volume of oxygen produced. Which graph represents the decomposition of an equal volume of a 20% solution under the same conditions?

• A

• B

• C

• D

Tags

NGSS.HS-PS1-5

The curve shows the volume of gas from a chunk of metal reacting with excess acid. Draw a curve showing how it would look if the same mass of powdered metal was used instead. Ask your teacher to check your answer before you submit.

Tags

NGSS.HS-PS1-5

In the following reaction, the rate of consumption for CaCO₃ is 0.12 g/s. Why can't we calculate the rate of formation of CO₂ by multiplying 0.12 g/s by the mole ratio?

• Because different chemicals have different molar masses.

• Because all the chemicals are in the gaseous state.

• Because they are a 1:1 ratio.

• Because the pressure and temperature are changing.

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-7

If the rate of consumption of CaCO₃ is 1.50 g/min, what is the rate of formation of CO₂ in g/min? Take your time to calculate it to 2 decimal places.
CaCO₃ → CO_{2 +} CaO

Answer explanation

Calcium carbonate convert to moles:

1.50 g / ((40.1 + 12 + (3 x 16.0)) g/mol = 0.015 mol

= 0.015 mol/min

1:1 mol ratio, so CO₂ is formed at 0.015 mol/min

Convert CO₂ to moles:

0.015 mol x (44.0 g/mol) = 0.66 g

Since original data was per minute, answer is 0.66 g/min

Tags

NGSS.HS-PS1-5

The rate of a chemical reaction normally

• increases as temperature decreases.

• decreases when a catalyst is added.

• increases as reactant concentration increases.

• decreases as reactant concentration increases.

Tags

NGSS.HS-PS1-5

Crushing a solid into a powder will increase reaction rate because:

• the particles will collide with more energy

• the orientation of colliding particles will be improved

• the activation energy barrier will be lowered

• the powdered form has more surface area

Tags

NGSS.HS-PS1-5