CP3 Investigating the Rate of Reaction

• What is the rate of reaction defined as?

  Change in concentration per time
• The formula for the rate of reaction is Rate = $\frac{\Delta \text{[Reactant / Product]}}{\Delta t}$
• The rate of reaction measures the speed at which reactants are converted into products.
• The rate of reaction is expressed in units of mol/L/s or mol L^-1 s^-1, which is equivalent to mol/L/s
• Why is it important to choose reactants with suitable concentrations?

  To allow measurable changes
• Extremely fast reactions may be hard to monitor accurately.
• Match the variable in the Arrhenius equation with its definition:

  $k$ ↔️ Rate constant

  $A$ ↔️ Frequency factor

  $E_{a}$ ↔️ Activation energy

  $R$ ↔️ Ideal gas constant

  $T$ ↔️ Temperature in Kelvin
• A catalyst lowers the activation energy, thereby increasing the reaction rate
• For a reaction producing gas, a gas syringe can measure the volume of gas produced over time.
• What is the unit time in the formula for reaction rate?

  Seconds
• Temperature influences reaction rates, as described by the Arrhenius equation.
• The rate of reaction measures how fast a reaction occurs.
• The rate of reaction is determined per unit of time.
• Key factors to consider when investigating the rate of reaction

  1️⃣ Reactant Concentrations

  2️⃣ Reaction Speed

  3️⃣ Observability

  4️⃣ Temperature

  5️⃣ Catalyst
• Observability is crucial for monitoring the rate of reaction.
• Match the variables in the Arrhenius equation with their meanings:

  k ↔️ Rate constant

  A ↔️ Frequency factor

  E_{a} ↔️ Activation energy

  R ↔️ Ideal gas constant

  T ↔️ Temperature in Kelvin
• Potassium iodide can act as a catalyst in the decomposition of hydrogen peroxide.
• Steps to set up the reaction apparatus for measuring the rate of reaction

  1️⃣ Prepare the Reaction Vessel

  2️⃣ Assemble Concentration Measurement Equipment

  3️⃣ Ensure Temperature Control

  4️⃣ Use a Stopwatch
• A water bath is used to keep the reaction temperature constant.
• Match the techniques for measuring reaction rates with their applications:

  Titration ↔️ Measuring concentration by reacting with a known substance

  Spectrophotometry ↔️ Measuring absorbance of colored substances

  Gas Collection ↔️ Measuring the volume of gases produced

  Gravimetric Analysis ↔️ Measuring the mass of a precipitate
• The Beer-Lambert Law relates absorbance to concentration and path length.
• A negative rate of reaction indicates a decrease in reactant concentration.
• Match the variables in the Arrhenius equation with their units:

  k ↔️ mol/L/s

  E_{a} ↔️ J/mol

  T ↔️ K
• What is the balanced chemical equation for the decomposition of hydrogen peroxide using potassium iodide as a catalyst?

  $2H_{2}O_{2} \rightarrow 2H_{2}O +$$O_{2}$
• The setup for measuring the reaction of hydrogen peroxide allows easy measurement of oxygen gas evolution
• High reactant concentrations always result in reactions that are easy to monitor.

  False
• The Arrhenius equation describes the relationship between reaction rate and temperature
• What does the term $E_{a}$ represent in the Arrhenius equation?


  Activation energy
• A catalyst increases the reaction rate by lowering the activation energy.
• Steps to set up a reaction apparatus for measuring reaction rates.

  1️⃣ Assemble a reaction vessel

  2️⃣ Attach equipment for measuring concentration changes

  3️⃣ Include a stopwatch or timer

  4️⃣ Use a thermometer if temperature is a variable
• For a reaction that produces gas, a gas syringe can be used to measure the volume of gas produced over time
• Match the technique with its description.

  Titration ↔️ React with a known substance

  Spectrophotometry ↔️ Measure absorbance of colored substances

  Gas Collection ↔️ Measure volume of gases produced

  Gravimetric Analysis ↔️ Measure mass of precipitate formed
• Spectrophotometry is used to determine the concentration of colored substances by measuring their absorbance.
• In titration, hydrochloric acid ($HCl$) reacts with sodium hydroxide ($NaOH$) to measure concentration
• What does gravimetric analysis measure?

  Mass of precipitate formed
• In a titration, a reactant reacts with a known substance
• Spectrophotometry measures the concentration of colored substances by measuring their absorbance.
• What does gas collection measure in reaction kinetics?

  Volume of gases produced
• The decomposition of hydrogen peroxide produces water and oxygen
• The rate of reaction is defined as the change in concentration per unit time.