Lawrie Ryan and Roger Norris Cambridge International AS and A Level Chemistry Coursebook Second Edition University Printing House, Cambridge cb2 8bs. Cambridge International AS and A Level Chemistry Coursebook (2nd Edition) – Lawrie Ryan and Roger Norris Fully revised and updated content matching new. Ryan and Norris. Cambridge International AS and Lawrie Ryan and Roger Norris. Cambridge .. in a solution. 2. Cambridge International AS Level Chemistry.
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Jan 7, Free Download Cambridge International AS and A Level Chemistry Coursebook (2nd Edition) in pdf. written by Lawrie Ryan and Roger Norris. Cambridge International AS and A Level Chemistry Coursebook (Cambridge International Examinations series) by Roger Norris. Read online, or download in secure PDF format. Read Online Now cambridge international as and a level chemistry coursebook with cd rom examinations roger norris Ebook PDF at our Library. Get cambridge.
The stoichiometry of the equation is 1 : 3 : 2 : 3. The large numbers that are included in the equation 3, 2 and 3 are called stoichiometric numbers. We can calculate exactly how much iron is needed to react with sulfur and the mass of the products formed by knowing the molar mass of each reactant and the balanced chemical equation. Worked example 3 Magnesium burns in oxygen to form magnesium oxide. We can calculate the mass of magnesium oxide formed.
Step 1 Write the balanced equation. Step 2 Multiply each formula mass in g by the relevant stoichiometric number in the equation. This is because the stoichiometry of the reaction shows us that for every mole of magnesium burnt we get the same number of moles of magnesium oxide. In this type of calculation we do not always need to know the molar mass of each of the reactants.
If one or more of the reactants is in excess, we need only know the mass in grams and the molar mass of the reactant which is not in excess the limiting reactant. Give your answer to 3 significant figures. Carbon monoxide is also formed. We can find the stoichiometry of a reaction if we know the amounts of each reactant that exactly react together and the amounts of each product formed. For example, if we react 4. The ratio of hydrogen to water is 1 : 1.
But there is only one atom of oxygen in a molecule of water — half the amount in an oxygen molecule. So the mole ratio of oxygen to water in the equation must be 1 : 2.
Cambridge International AS and A Level Chemistry Coursebook (2nd ed.)
Check-up Check-up 5 a Sodium reacts with excess oxygen to form sodium peroxide, Na2O2. Use this information to calculate the stoichiometry of the reaction.
The examples show the number Worked example 5 How many moles of calcium oxide are there in 2. The least number of significant figures in the data, however, is 2 the mass is 2. So your answer should be expressed to 2 significant figures, as 0. Note 1 Zeros before a number are not significant figures. For example 0. Note 2 After the decimal point, zeros after a number are significant figures.
Note 3 If you are performing a calculation with several steps, do not round up in between steps. Round up at the end. Percentage composition by mass We can use the formula of a compound and relative atomic masses to calculate the percentage by mass of a particular element in a compound.
We can calculate the mass of iron that can be obtained from Fe2O3 by using molar masses. The molecular formula of a compound shows the total number of atoms of each element present in a molecule. Table 1.
Fact file An organic compound must be very pure in order to calculate its empirical formula. Chemists often use gas chromatography to purify compounds before carrying out formula analysis. So the empirical formula of magnesium oxide is MgO. Explain why these beads are used rather than having large lumps of catalyst.
Over recent years the concentration of acids in rainwater all over the world has been steadily increasing. The acids in the air react with the marble and damage the surface of the building. The higher the concentration of acid in the air, the quicker a building made of marble or limestone will react.
This damage increases as the concentration of the acids in rainwater increases. Cars with steel bodies are likely to rust faster if you live near the sea because there is a higher concentration of salt in the atmosphere and rainwater.
How changing the concentration of acid affects reaction rate The rate of reaction of marble chips calcium carbonate is carried out with hydrochloric acid of different concentrations.
The temperature, mass and size of marble chips are kept the same as well as the volume of hydrochloric acid used. The concentration of hydrochloric acid is varied but it is always in excess. For each concentration of hydrochloric acid used, record the volume of gas at time intervals.
Chemistry IGCSE. Sample Chapter. for. Roger Norris. Series Editor:
A graph of the results is shown. Delivery tube Marble chips Rubber bung Gas syringe Hydrochloric acid You can see that as the concentration of acid increases, the rate of reaction increases. The final volume of carbon dioxide released is the same in each experiment because hydrochloric acid was in excess.
Using the collision theory A concentrated solution has more particles of solute per unit volume than a dilute solution. In the reaction between calcium carbonate and hydrochloric acid, the important solute particles are the hydrogen ions in the hydrochloric acid see Unit The more concentrated the hydrochloric acid, the more hydrogen ions there are in a given volume to collide and react with the carbonate particles in the calcium carbonate.
The rate of reaction depends on the number of successful collisions per second. If there are more collisions per second, the rate of reaction is faster. Calcium carbonate particles Figure Water molecules not shown Low concentration of acid Few acid particles ions per dm 3. Less chance of particles colliding and reacting. The frequency of collisions is low. High concentration of acid Many acid particles ions per dm 3. More chance of particles colliding and reacting.
A level chemistry textbook
The frequency of collisions is high. In a reaction involving gases, increasing the pressure has a similar effect to the increase in concentration.
Increasing the pressure pushes the particles closer together so that they collide with a greater frequency and the rate of reaction increases. It is the more frequent collision of the particles which is important. Sketch a graph to show how the mass of the reaction mixture changes using dilute hydrochloric acid.
When the reactants are more there are more reactant particles present per volume so they more. Food goes mouldy quicker when left out of the refrigerator. This is because the reactions which make food rot are faster at higher temperatures. Some surgical operations are carried out below room temperature to slow down the chemical reactions in the body. PRACTICAL Investigating the effect of temperature on reaction rate Time how long it takes for the A to disappear when viewed from above Sodium thiosulfate solution and dilute hydrochloric acid Moving faster means it s more likely that you ll bump into someone else and the bump will be harder too!
Food cooks quicker at a higher temperature because the particles have more energy and there are more collisions per second between the molecules in the food. When we react sodium thiosulfate with hydrochloric acid a precipitate of sulfur is formed.
You place the flask of sodium thiosulfate on top of the cross on the paper. You add hydrochloric acid and record the time taken for the letter X to disappear. Repeat the experiment at different temperatures using the same amounts of acid and thiosulfate heated up separately before mixing them together.
Time taken for solution to go cloudy Figure Temperature You can plot a graph of the time taken for the X to disappear against temperature.
The shorter the time taken for the X to disappear, the faster the reaction is. This is because rate of reaction is proportional to amount of product formed or reactant used divided by time.
If you look at the graph carefully, you can see that for every 10 C rise in temperature, the rate of reaction approximately doubles. The second of these is the most important. When we heat up a reaction mixture, the particles gain energy. When particles gain energy they move faster and collide more often.
The frequency of collisions is increased. This results in an increased rate of reaction. In order to react, particles must collide with a minimum amount of energy.
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This is called the activation energy. As the temperature gets higher more and more particles have this minimum amount of energy to react when they collide. In other words, as the temperature is increased there is more chance of a collision between the reactant particles being successful. We say that the number of effective collisions increases as the temperature increases. Particles have less energy. They move more slowly and collide less frequently.
The collisions are not very effective. Higher temperature. Particles have more energy. They move faster and collide more frequently. The collisions are very effective. Note that as the temperature increases, each particle collides with a greater force.
It is also more accurate to write that there are more frequent collisions than just more collisions. At each temperature she recorded the volume of gas produced 30 seconds from the start of the reaction.
Sketch a graph to show how the volume of gas changes with temperature. At a higher temperature there are also particles with the amount of energy to react when they collide. So the collisions are more and the rate of reaction. The collisions that take place are also more energetic so are more likely to result in a reaction taking place. The only ones you have to know about are photosynthesis, the conversion of silver bromide to silver and the reaction of halogens with chlorine see Unit These are called photochemical reactions.
We rely on the photochemical reactions in plants to provide the oxygen we breathe and the food we eat as well as removing carbon dioxide from the atmosphere.
The photochemical reaction in plants is called photosynthesis. Not all photochemical reactions are useful. Compounds called CFCs are broken down by ultraviolet light and the products are responsible for the depletion of the ozone layer around the Earth.
Photosynthesis Plants use the energy from sunlight to make glucose. This process is called photosynthesis. You can record the volume of oxygen collected over several days. Then you can repeat the experiment using stronger more intense light. The graph shows how the rate of photosynthesis changes with light intensity. The graph levels off because carbon dioxide becomes limiting. Photo: Two plants grown with and without light Light source Small glass syringe Volume of oxygen Weak light Light intensity Strong light Water Funnel Pondweed The plant on the left looks unhealthy because it has not had enough light 17 Photography The surface of black and white photographic film contains tiny crystals of silver bromide mixed with gelatine.
When light shines on the film the silver bromide is activated. Some of the silver bromide decomposes breaks down to form silver. This is a redox reaction see Unit 9. The silver ions get reduced because they accept electrons and the bromide ions get oxidised because they lose electrons see unit 9.
The greater the intensity strength of the light the faster the reaction. A positive print is made by shining light through the negative onto a piece of photographic paper behind.
Some spectacle lenses darken in bright light and get more transparent in dim light. This is because light reacts with the silver chloride in the lenses. The paper and disc are then left in the light. After a short time the paper will turn black but if you remove the disc you can still see a circle of white paper.
This shows that light is needed for the reaction to happen. These reactions are photochemical reactions.This has been given a mass of exactly 12 units. This is very close to 1 and most Periodic Tables give the Ar of hydrogen as 1. Worked example 10 A compound has the empirical formula CH2Br. The mass spectrum of neon has three peaks: In December , while working under the direction of Charles Kettering at Dayton Research Laboratories , a subsidiary of General Motors, Midgley discovered that the addition of tetraethyllead to gasoline prevented "knocking" in internal combustion engines.
To overcome this problem, we have to weigh a lot of atoms.
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