- Join over 1.2 million students every month
- Accelerate your learning by 29%
- Unlimited access from just £6.99 per month
GCSE: Aqueous Chemistry
Currently browsing by:
- Removefewer than 1000 words
Meet our team of inspirational teachers
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!
This means zinc will be third in the reactivity series out of the 4 metals. And Iron, which is less reactive than calcium, magnesium and zinc, will produce the least amount of heat out of the 4 metals and is lower than calcium, magnesium and zinc in the reactivity series. Apparatus/method Hydrochloric acid Water (to dilute acid) Data logger (to take temperature) 4 temperature sensors Magnesium 1 mole Iron 1 mole Zinc 1 mole Calcium 1 mole Measuring cylinder 4 polystyrene cups with 4 lids (trap heat) Safety glasses Method An equation for the reactions: Magnesium + Hydrochloric acid > Magnesium chloride + Hydrogen Mg(s)
- Word count: 751
This does 3 tons per hour and the machine was bought second hand for �8500 + �15000 to install. The grist is passed on to grist cases. At 5.30am, the mash man opens the hot liquor (water) tank at 200deg.F and lets this into the mash tuns. This dissolves the sugars. Plates on the bottom of the tuns hold back the husks. The temp. is 150 deg F + 0.5 deg. F. This is called the sweet wort. This temp. encourages activity of the enzyme beta amylase, which only partly breaks down the large starch molecules into maltose sugar molecules.
- Word count: 605
Also the plant type is another variable i.e. the barley plant could be immune to weak acid or it could effect barley more than the wheat plant. This experiment is not very reliable so I would do it at least three times to get a clear set of results unfortunately I can only do the experiment once because of time restrictions. To evaluate if the experiment was a success and weather my results are reliable or not I will have to compare my results with another group. The safety aspects in this experiment, which I will have to take into consideration Will be wearing safety goggles when using
- Word count: 987
This water is carried long distances by winds and then returned to Earth as rain, fog, or snow. Acid rain may also be caused by natural occurrences such as fires, wind-eroded soils, and volcanic eruptions. However, natural processes lead to a slow acidification of lakes and forests and are not the cause of the current controversy. Effects of Acid Rain Acid rain can cause some serious problems. Among these are: * the acidification of lakes and streams * forest damage * decay of buildings and paint * reduction in visibility * an increase in public health problems LAKES AND STREAMS Natural lakes and streams have an acidity of between 6 and 8.
- Word count: 602
The alcohols we will be using are: butanol, methanol, ethanol, and propanol. We will heat the set amount of water in a metal beaker. The water will be heated from room temperature, to 50 degrees Celsius. The height of the beaker will also remain The same height, which for us was 15cm, we found this the best height, as the flames tip just touched the beaker, which reduced heat loss which would result in less reliable figures.
- Word count: 250
Prediction When the concentration of acid increases, more gas will be given off faster. I know this from my trial experiments. Method Since I will be working with acid, I will wear safety goggles while conducting the experiment. I will use 1gram Marble chips that are all ground down to roughly the same size, and I will use 20cm3 of HCL of different concentrations ranging from 0.4M - 2M I can measure the reaction by how much gas is given off. When the experiment takes place, I will take the reading after 2 minutes to get a graph for the results.
- Word count: 917
To investigate the factors affecting the rate of reaction of calcium carbonate (limestone) with hydrochloric acid
PREDICTION: I predict that as the temperature of the acid increases, the rate of reaction will increase. This is because, when a liquid is heated, the particles move faster and have more collisions, which will increase the rate of reaction. FACTORS: The things that could change, that would affect the rate of reaction are: Surface area- crush limestone The strength of acid- moles The mass of limestone The temperature of the acid The amount of acid used Adding a catalyst Pressure VARIABLE: I am going to change the heat of the acid. I will heat it first at 30C, then 40C, 50C, 60C and then 70C.
- Word count: 747
To find out how temperature will effect the rate of reaction between sodium thiosulphateand hydrochloric acid.
higher the temperature the less time it will take to go a cloudy colour because particles 2cxv5 Diagram: Method: Collect all the apparatus and set them all up as it is shown in the diagram above.
- Word count: 261
+ 2HCL(aq) = CO2(G) + H2O(l) + CACL2(aq) Method � Set up apparatus as shown in diagram. � Weigh the correct mass of limestone. � Add acid to the limestone and record the change in mass. � Repeat for each chip size. Safety � Be careful handling the acid.
- Word count: 411
Which concentration of acid when reacted with marble pieces gives off the largest volume of gas in the fastest time?
You then repeat the experiment five more times but for each time you take 5ml of acid away and replace it with distilled water this is so you keep the mass the same. Safety * Always tie back hair and loose clothing * Always wear safety glasses especially when using acids. * Any spillages report to your teacher immediately * Any breakages report to teacher immediately Variables Keeping the same * The amount and the size of marble will be kept the same.
- Word count: 895
A stop watch to record the time of the experiment 6. Pestle and mortar to crush the calcium carbonate into powder 7. A burette to measure accurately the Hydrochloric Acid The method I am going to use to perform my experiment are- 1. Set up apparatus 2. Measure out 25cm3 of acid using a burette (accurately) 0.1cm3. 3. Weigh out 1g of marble chip to the nearest 0.01g 4. Add marble to acid, put the bung in + measure CO2 gas given off at 30 seconds, record the co2 given off.
- Word count: 997
Chemical Economics Investigation: - speeding up the reaction speed between calcuim carbonate and hydrochloric acid.
Before I could start the experiment I had to predict how much hydrochloric acid is was going to use and how much calcuim carbonate I needed, you can see how I did this by looking at the equation below: - * I have to remember that 1 mole of any gas occupies 24,000cm cubed at room temperature and pressure. Word equation Calcium carbonate + Hydrochloric acid Calcuim chloride + Water + Carbon dioxide Balanced equation CaCO3 + 2Hcl CaCl2 + H2O + Co2 Relative formula masses 40+12+16+16+16 2*(1+35.5)
- Word count: 927
To find out how concentration affects the rate of reaction between Calcium Carbonate and Hydrochloric Acid.
* Concentration Amount of gas * Mixed or not How long it took to collect 'x' amount * Amount Practical Method: Set up the apparatus as shown in the diagram. Making sure the inverted measuring cylinder is full of water. Place end of rubber tubing inside the cylinder.
- Word count: 408
Temperature of reactants. The higher the temperature of the reactants, the more energy they have. This will make the particles move quicker and .the chances of successful collisions will be increased. Cold acid. the acid particles are moving slowly and do not have enough to have many successful collisions. Hot acid. the acid particles are now moving much faster with more energy, so most collisions are likely to be successful. Apparatus: Water bath, Stand, Boss, Clamp, Bungs - vented, Measuring Cylinder, Container, Stop watch, Ice, Conical flasks, Thermometers, Calcium carbonate chips, Hydrochloric acid, Scales. Safety: I shall be wearing all different sorts of protective clothing such as Gloves - for handling hot objects, Lab coat
- Word count: 775
My chosen variable is concentration. The other variables in the experiment that would affect the rate of reaction are temperature of the mixture and the surface area of calcium carbonate. The apparatus will be set up as shown in the diagram and will be kept this way for each individual experiment so that it is a fair test. Other factors we need to keep constant so it is a fair test are all the variables: temperature and surface area. Not concentration as this is the variable we are testing.
- Word count: 738
To find out how quickly 25mls of Sodium Thiosulphate of different temperatures reacts with Hydrochloric acid to turn the solution cloudy.
Whilst this was heating I set up the rest of my equipment as is shown. I placed my empty conical flask on top of the cross and added 5ml Hydrochloric acid to it. When the Sodium Thiosulphate had reached the correct temperature I added it to the acid and started the clock, I stopped the clock when looking from above I could not see the cross on the paper any more. I repeated each temperature 3 times and took an average for it in order to make it more of a fair test. I performed the experiment for 5 different temperatures, these were as follows: 70?, 60?, 50?, 40?
- Word count: 762
An equal amount of hydrogen and hydroxide ions react and form together to form a neutral solution. ACID + BASE SALT + WATER (Hydrochloric acid + Sodium hydroxide Sodium chloride + Water) PREDICTION I predict that there must be an equal amount of hydrochloric acid and hydroxide for neutralisation to occur. If this happens sodium chloride will be produced to form a reaction that will be neutralised. EQUIPMENT 50cm3 burettes Conical flask Sodium hydroxide (0.5m) Hydrochloric acid (0.5m) Universal indicator Pipette droppers 25cm3 measuring cylinder Thermometer Safety goggles PICTURE OF EQUIPMENT SET UP PROCEDURE 1. Collect all the necessary equipment and put it together ready for the experiment to begin.
- Word count: 992
My aim of this experiment is to find out the concentration of NaOH by titration with standard o.1dm3 Hcl solution.
= 23.9 cm3 to dm3 23.9 ÷ 1000 = 0.0239dm3 First working out the number of moles from the burette Moles = c × vdm3 C = 0.1, v = 0.0239 Moles = 0.1 × 0.0239 = 2.39 ×10-3 Step 2 working out the Concentration of NaOH in the flask C = mole ÷ v dm3 V = 25 cm3 ÷ 1ooo =0.025dm3 C = 2.39 ×10-3 ÷ 0.025 = 0.0956 moledm3 The strongest and weakens of the experiment. During the experiment there are some of the human error that occurred , which include reading the burette wrong or adding the wrong amount of Hcl solution ,this lead us to get a different results .
- Word count: 722
Hydrogen Fuel Cells use two reactants; Hydrogen and Oxygen. These can possibly be sourced from the electrolysis of water, powered by electricity from solar panels, or wind turbines, for a fully emission-free power method. The Hydrogen enters the cell at the anode side of the cell, whereas the oxygen enters at the cathode side of the cell.
- Word count: 465
Plan to investigate the factors that affect the rate of reaction between sodium thiosulfate and hydrochloric acid
This increases the rate of reaction, as there are more successful collisions per second while a lower temperature would decrease the rate of reaction. Changing the concentration of the reactants - This would affect the results of the experiment because the concentration is a measure of the number of particles per unit volume. As the concentration of a solution increases, there are more reactant particles in the same volume and this increases the chances of particles colliding with each other.
- Word count: 852
Some metals are magnetic, meaning that they can be turned into or attracted to magnets. This quality means that a magnet can be used to separate substances such as iron that are separatable from non-magnetic substances. However, other materials can be dissolved in water, to form a solution. Another method of separating mixtures is through evaporation. This method is often used to extract an un-dissolved material (such as salt) from a mixture containing water. In this case, if a mixture containing sand and water were left at room temperature, the water would evaporate, leaving only the sand at the bottom.
- Word count: 467
oxide once Malachite has decomposed. Controlled: Temperature Malachite is heated to Time Heated (Until Malachite completely decomposes) Method: Note: For safety reasons, wear a protective mask while experimenting with the decomposed copper (II) oxide as it is toxic when inhaled. 1. A varying amount of malachite is added to a dish 2. The malachite is stirred until it becomes a powder with an even composition. 3. While continuing to stir, heat the malachite on a hot plate to 200 degrees Celsius. Continue heating until the green malachite fully decomposes (indicated by the completely black colour of copper (II)
- Word count: 838
We tested this by filling a beaker with different temeperature's ranging from 0 degrees celecius to 100. We recorded the time range of the dissolving sugar cube. This is how we tested our question. I expected the results that were gotten. Hypothesis: If temperature increases than the dissolving rate of a sugar cube will increase.
- Word count: 433
+ Mg(s) ? MgCL2(aq) + H2(g) Hydrochloric Acid + Magnesium ? Magnesium Chloride + Hydrogen Method 2 : Acid + Insoluble Base 1. Neutralisation reaction 2. When Acid and Base react ? Salt and Water is formed 3. The salt made depends on the acid used and the metal in the base/alkali - (e.g.
- Word count: 481