GCSE: Aqueous Chemistry
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The rates of aqueous reactions
- 1 The rate of reaction can be increased by increasing the concentration of the solution. This will mean there are more molecules in the same amount of space, so there will be more collisions.
- 2 The rate of reaction can be increased by increasing the temperature of the solution. This will give the molecules more energy, making them move faster and collide more. It will also mean they stand a better chance of having the activation energy.
- 3 The rate of reaction can be increased by increasing the pressure of the solution. This will mean there are more molecules in the same amount of space, so there will be more collisions.
- 4 Adding a catalyst to the solution will increase the rate of reaction. This is because the catalyst lowers the activation energy needed for the solution to react.
The definition for rate of reaction is “change in concentration of product or reactant over time”.
It has the units mol dm-3 s-1
How to calculate the number of moles in a solution
The two most important equations to learn are:
moles = mass / Mr and moles = volume x concentration
If you know the moles of one chemical in your balanced equation, you can find out the moles of anything else by looking at the “big number” ratios. For example:
2NaOH + H2SO4 = Na2SO4 + 2H2O
If you had 10 moles of H2SO4, because there is a 2:1 ratio, you would have 20 moles of NaOH.
- 3 Your volume MUST be converted into dm3 before you use it in your equation. To convert cm3 into dm3 divide your number by 1000.
- 4 Do not forget to round your answer to a sensible number of significant figures (usually the least amount of significant figures that the question itself goes to).
- 5 Your Mr can be found by looking at the mass number on the periodic table (this is the bigger of the two numbers- the smaller one is called the proton number
Top tips for aqueous reactions
- 1 Anything that is dissolved in an aqueous solution will have the state symbols (aq). For Na+(aq)
- 2 If your reaction is dissolved in water, then water will have the state symbol (l), for “liquid”.
- 3 If the question says that your reaction is done under standard conditions, then it means at 1 atmosphere of pressure, at 25'C.
- 4 When constructing balanced reactions, do not forget to balance your charges when making salts. For example: HCl + Mg = MgCl + 0.5H2 would be wrong. The correct answer would be 2HCl + Mg = MgCl2 + H2.
- 5 The most important equation reaction to remember is acid + base = salt + water. This crops up all of the time in exams!
1,413 GCSE Aqueous Chemistry essays
- Marked by Teachers essays 25
- Peer Reviewed essays 19
To determine the amount of ammonia in a sample of household cleaning product, 'cloudy ammonia', in the form of NH4OH through the process of volumetric analysis.5 star(s)
A five star piece of work. Excellent introduction shows a clear understanding of titration and shows good balanced equations. The procedures are excellent and the results show accuracy and lots…
- Essay length: 1805 words
- Submitted: 18/08/2006
- Marked by teacher: Patricia McHugh 08/04/2013
Biology Practical Investigation to find the lowest concentration of Copper Sulphate solution that will denature egg albumen.5 star(s)
An excellent description of the structure of proteins.
The report is good thus far, consider how you could make the experiment more reliable (repeats) and how you…
- Essay length: 804 words
- Submitted: 23/02/2004
- Marked by teacher: Jon Borrell 08/01/2013
Investigation into the effect of acid/alkali strength on the heat change when acids and alkalis are mixed5 star(s)
This is a five star piece of work. The investigation is explained in detail and in a clear order so the reader can easily follow the plans. Excellent predictions made…
- Essay length: 2282 words
- Submitted: 21/08/2003
- Marked by teacher: Patricia McHugh 08/04/2013
Conductivity Lab. Purpose: To determine which substances are ionic and which are molecular based on their ability to conduct electricity4 star(s)
This is a good account of conductivity. It contains a well through out experiment to confirm whether a broad range of materials conduct. The report does not go into much…
- Essay length: 1012 words
- Submitted: 03/01/2012
- Marked by teacher: Brady Smith 17/06/2012
- Reviewed by: dragonkeeper13 29/06/2012
Back Titration Lab Report. In my experiment, I hoped to find the amount of calcium carbonate in some mineral limestone using the back titration method4 star(s)
This is a four star piece of work with excellent scientific knowledge of molar calculations and demonstrated great skill in their work. A clear, concise piece of work but they…
- Essay length: 737 words
- Submitted: 04/10/2011
- Marked by teacher: Patricia McHugh 01/12/2012
This is a very well written report. The experimental method is evaluated with preliminary tests used to refine the experimental method. The data is robust and reliable. The main limitation…
- Essay length: 4385 words
- Submitted: 05/04/2009
- Marked by teacher: Cornelia Bruce 17/04/2013
Investigate the effect of changing the concentration of sodium hydroxide (alkali) on the volume of hydrochloric acid needed to neutralize a fixed volume of alkali by measuring the temperature and noting colour changes of the solution mixture.4 star(s)
This is a very good investigation write up, looking at neutralisation and the factors that have an effect on it. There is no graph included within the write up,…
- Essay length: 3494 words
- Submitted: 09/02/2005
- Marked by teacher: Louise Star 21/06/2013
This is a good account of a water heating experiment. It contains a well thought out experiment to confirm the relationship between water mass and heating. The…
- Essay length: 2653 words
- Submitted: 27/10/2003
- Marked by teacher: Cornelia Bruce 01/12/2012