Ocr Gateway Chemistry B Coursework

Is this a good enough hypothesis to get an A*?
My hypothesis is that dissolving Hydrochloric acid (HCl) in a small volume of water makes de-scaling quicker because there will be a higher concentration of acid, meaning that there will be more acid particles in a given volume, therefore there will be more available to react with Limescale (of which the main component is calcium chloride, CaCO3), meaning collisions between acid and Limescale particles will be more frequent and therefore there will be more successful collisions in a given time period, meaning a faster rate of reaction and therefore faster de-scaling than if the Hydrochloric acid was dissolved in a larger volume of water.

Also, any other help or tips to get top marks when planning the experiment or any other steps?

When writing a hypothesis for GCSE, I was taught that you needed to use the following format for top marks (and it did indeed bring me top marks in this section):
"If the...[dependent variable]...is related to the....[independent variable]...then this may result in....this is because...."
e.g. for your one, you should write "if the volume of HCl dissolved in water is related to the amount of descaling, then a small volume of water may result in descaling being quicker. This is because...[provide your reasoning/science/explanation]"

One key thing to note however, is because this is a HYPOTHESIS, you need to use words that denote uncertainty like "may" or might" or "should" etc throughout the entire hypothesis - do not write "will" (because that suggests you already know the answer before doing the experiment!).

Other tips:
-make sure your plan includes a diagram, method, risk assessment, identification of dependent, independent and controlled variables, results table
-make sure your plan also includes controlled variables and why/why not it may be possible to control them (I included some things like how temperature/pressure could affect it)
-for the risk assessment, it would be a very good idea to use the following headings: hazard (e.g. name of chemical), risk (e.g. toxic), how risk will be minimised(e.g.will be handled with care,not swallowed), what would happen if risk occurred(e.g.choking), action taken if risk occurred(first aid,ambulance called if serious)
-when drawing the results table, include units of measurement and headings
For the evaluation:
-make sure you label the axes, draw at least one graph for the evaluation bit- also do a few mathematical calculations
-make sure the research includes at least 3 (hopefully more sources)
-get in as much scientific info as you can for the evaluation (many students fail to do this and just describe their results) and make sure to make many links between your research and your experiment, identifying anomalies etc

Это как будто деление на ноль. - Что. - Деление на ноль, - сказала она, пробегая глазами остальные данные.  - Средняя цена определяется как дробь - общая стоимость, деленная на число расшифровок. - Конечно.

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