Question | Answer |
What is reaction rate? | The change in the amount of reactants or products per unit time (normally per second) |
What does continuous monitoring measure? | How the amount of a product or reactant changes over the complete course of the reaction |
Name the two methods used to continuously monitor the formation of a gas | Using a gas syringe (recording volume at regular time intervals) Measuring change in mass |
What piece of equipment is used to measure a colour change? | Colorimeter (measures absorbance of a particular wavelength of light) |
Outline the method for using a colorimeter to measure a colour change | 1. Set the colorimeter to measure the wavelength of light you're interested in measuring 2. Calibrate the colorimeter (place sample of distilled water in colorimeter and set the absorbance to 0) 3. Carry out reaction - place samples from reaction mixture at regular intervals in a cuvette and measure absorbance |
Complete the sentence: If either _______________ or _____________ ions are produced or used up in a reaction, then you can monitor the ______________ of the reaction by measuring the ___________ i the pH | If either HYDROGEN or HYDROXIDE ions are produced or used up in a reaction, then you can monitor the PROGRESS of the reaction by measuring the CHANGE in the pH |
What is initial rate of reaction? | The rate at the start of the reaction |
How can you calculate the initial rate of a reaction using a graph? | Calculate the gradient of the tangent at time = 0 in a concentration-time graph |
The initial rates method is used to find out how the initial rate varies as you change the initial concentration of one of the reactants. Why is it harder to use continuous monitoring experiments instead? | The initial rates method is easier than doing multiple continuous monitoring experiments and finding each initial rate from a concentration-time graph |
Describe the initial rates method | Time how long it takes for a set amount of product to forma t the beginning of the reaction in order to calculate an initial rate for a reaction |
Are clock reactions a type of initial rates or continuous monitoring reaction? | Initial rates reaction |
What happens during a clock reaction? | The formation of a set amount of product is shown by a sudden, visual change in the reaction mixture |
Outline the method for a clock reaction | 1. Add a known amount of the substance that reacts with the product you're interested in to the reaction mixture 2. The product reacts with that substance, producing a sudden change in colour 3. This is the endpoint of the reaction |
What are the 3 assumptions made when carrying out a clock reaction? | The concentration of each reactant doesn't change significantly over the time period of your clock reaction The temperature stays constant When the endpoint is seen, the reaction has not proceeded too far |
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