You're viewing 1 free preview question for Chemistry HL — subscribe to unlock 158 more, plus the Full Question Bank, Mock Papers & Worksheets.Upgrade

How Fast? The Rate of Chemical Change · Paper 2 — Free Chemistry HL Practice Questions

1ChallengeSAQ-LRate law and order of reactions9 marksPaper 2~14 min

Data

t\,/\,\text{s}

—

0

—

120

—

240

—

360

—

480

—

600

[\text{OH}^-]\,/\,\text{mol}\,\text{dm}^{-3}

—

0.100

—

0.075

—

0.056

—

0.042

—

0.032

—

0.024

Ethyl methanoate (

\text{HCOOC}_2\text{H}_5

) undergoes hydrolysis in alkaline solution:

\text{HCOOC}_2\text{H}_5\text{(aq)} + \text{OH}^-\text{(aq)} \rightarrow \text{HCOO}^-\text{(aq)} + \text{C}_2\text{H}_5\text{OH(aq)}

A student investigates the kinetics at

25\,^\circ\text{C}

with initial concentrations

[\text{ester}]_0 = [\text{OH}^-]_0 = 0.100\,\text{mol}\,\text{dm}^{-3}

. Samples are withdrawn and titrated with standard acid to give the following

(a)

Using the data above, show that the reaction is second order with respect to

\text{OH}^-

. [2 marks]

(b)

Calculate the rate constant

k

, including its units. [2 marks]

(c)

Explain why the order with respect to the ester cannot be determined from this data alone. [2 marks]

(d)

A student proposes repeating the experiment using

[\text{ester}]_0 = 0.100\,\text{mol}\,\text{dm}^{-3}

and

[\text{OH}^-]_0 = 1.00\,\text{mol}\,\text{dm}^{-3}

. Deduce how this modification allows the order with respect to the ester to be determined, and identify what quantity should be plotted to confirm a first-order dependence on the ester. [3 marks]

Solutions

Questions 2-159

Unlock these questions with Premium

That's every free question here — 1 of 159.

+158 more questions, plus Mock Papers & Worksheets, are waiting in Premium.

Upgrade