Chemistry Practical Flashcards
What are the key things to remember for the Planning/Method section.
- You need 4 different key variables
- You need to identify the independent variable, dependent variable and control variables. (2 out of the 3 variables need to be stated. Remember to talk about surface area and temperature.) For all of the variables remember to use numbers and explain how=from… until….
What are the key things to remember for the Data/Graph section.
Remember the correct units:
• t (s)
• °C
• %
What are the key things to remember for the Conclusion
You must talk about the concentration and the rate of reaction.
What are the key things to remember for the Discussion section.
- You need to remember to relate to PARTICLES
* Remember to talk about the instruments (SENSITIVITY) which one & why.
What do you need to write for the plan section of the exam?
Write what you are planning to do. For example:
I am diluting solution A by 75%, 50%, 25% and 0%. I am then mixing the solutions and recording the reaction time. I am timing how long it takes the mixed solutions to fully change colour.
What do you need to write for the “Other Variables that may affect your results” section
Write anything that could affect your results. For example:
After rinsing a test tube it has water particles left in it which could affect the concentration of the solution, so I am drying them before re-using.
What do you need to write for the “note any changes to the initial procedure” section
I changed the concentrations I was measuring from 93% to 90% and 87% to 80%. This is because it is faster to work out the concentration needed for a round number than an odd number. I need to use my time wisely and choose the quickest possible options.
What is the layout for the method
Independent variable: Concentration
I changed the concentration to; 20%, 50%, 80%, 100%
Dependent variable: Time measured with a stopwatch from when all of the solution has been poured in, until all of the solution has turned dark.
Control variable: The concentrations were: 20%, 50%, 80%, 100% measured with a measuring cylinder.
Method: Must include:
• What you changed and how
• What are you measuring and how
• What are you keeping the same and how
• Repeats
• Any other relevant
• Use numbers and the correct symbols and terminology.
How do you layout your graph
- Time (s) on the left hand side.
- Concentration of solution (%) on the bottom (x axis)
- concentration going from left to right, lowest to highest concentration.
- Start from 0,0 and use correct spacing between the numbers.
What do you need to write for the conclusion
As concentration decreases the time increases hence the rate of reaction decreases. I know this because my average time for 100% solution was;____ my average time for 80% was;____ my average time for 50% was;___ and my average time for 20% solution was;____.
What do you need to write for the Accuracy section
- What were the control variable and what were they measured with…. why…..
- __mL of __ measured with a measuring cylinder because there needs to be the same number of ___ particles in each trial.
- draw test tube with arrow pointing out from top of liquid measured at eye level to avoid PARALLEX error and at the bottom of the meniscus (the curved part).
- The temperature was room temperature, which was ___ on the day, measured with a thermometer. This needs to be the same in order to have the same kinetic energy.
- The concentrations were ______________ measured with a measuring cylinder.
- Surface area?
What do you need to write for the Reliability and Validity section
- I measured the time with a stopwatch because it is a better instrument (more accurate and sensitive) than a clock.
- I used 5 mL and 10mL measuring cylinders. They are more accurate and reliable compared to a beaker of larger measuring cylinder.
- I repeated each concentration trial 3 times to eliminate any outliers and overall eliminate any error due to reaction times; and any other inconsistancies.
What do you need to write for the discussion section.
When the concentration is higher there are more particles in the same space therefore more collisions per second therefore a greater rate of reaction.
What is the independent variable
Something you decide to change: you need at least 4 different Concentrations. You need to say what is it and how will you measure it.
What is the dependent variable
What you measure as a result. How (from…until….), with what. The dependent variable is: Time measured with a stopwatch from….. until….
