Firstly, let's think about some different types of reactions and how quickly or slowly they occur. For each of the reactions above, write a balanced chemical equation for the reaction that takes place. Combustion is the fastest and weathering is the slowest.
The order of reactivity from fastest to slowest is: combustion, photosynthesis, rusting, weathering.
Answers could include mention of the fact that coal and paper burn fast, whereas rocks do not disappear overnight. Also plants use photosynthesis to make food and this process has to happen relatively fast but not too fast. Think of some other examples of chemical reactions. How fast or slow is each of these reactions, compared with those listed earlier? This video is a simple demonstration of how a change in surface area can affect the average rate of a reaction.
You can see how quickly the fuel burns when spread over the table. Think about how much more fuel would be needed to cook a meal if you had it spread over a large surface area rather than kept in a container with a small surface area. In a chemical reaction, the substances that are undergoing the reaction are called the reactantswhile the substances that form as a result of the reaction are called the products.
The reaction rate describes how quickly or slowly the reaction takes place. So how do we know whether a reaction is slow or fast? One way of knowing is to look either at how quickly the reactants are used during the reaction or at how quickly the products form.
For example, iron and sulfur react according to the following equation:. In this reaction, we can observe the speed of the reaction by measuring how long it takes before there is no iron or sulfur left in the reaction vessel. In other words, the reactants have been used. Alternatively, one could see how quickly the iron sulfide the product forms. Since iron sulfide looks very different from either of its reactants, this is easy to do.
In this case, the reaction rate depends on the speed at which the reactants oxygen gas and solid magnesium are used, or the speed at which the product magnesium oxide is formed. The average rate of a reaction describes how quickly reactants are used or how quickly products are formed during a chemical reaction. The average rate of a reaction is expressed as the number of moles of reactant used, divided by the total reaction time, or as the number of moles of product formed, divided by the total reaction time.
Calculate the rate of the reaction. A number of different reactions take place.Search this site. Periodic Table. Nutshell Revision Topic 1 - States of Matter. Topic 2 - Acids, Alkalis and Salts. Topic 3 - Atomic Structure. Topic 4 - Ionic Compounds. Topic 5 - Covalent Substances.
Topic 6 - Oxygen and Oxides.
Chem4Kids Quiz: Rates of Reaction
Topic 7 - Group 1 elements. Topic 8 - Group 7. Topic 9 - Hydrogen and Water. Year 9 - Revision Checklist. Year 9 Prep Booklet. Topic 01 - The Periodic Table. Topic 02 - Moles. Topic 04 - Empirical Formulae and Percentage Yield.Integrated Rate Law Problems, Zero, First & Second Order Reactions, Half Life, Graphs & Units
Topic 05 - Energetics. Topic 06 - Rates of reaction. Topic 07 - Equilibria. Topic 08 - The industrial manufacture of chemicals. Topic 09 - Metallic crystals. Topic 10 - The Reactivity Series. Topic 11 - Electrolysis. Topic 12 - Extraction and uses of metals. Topic 13 - Tests for ions and gases. Year 10 Prep Book. Year 10 Revision Checklist. Topic 1 - Alkanes.
Topic 2 - Alkenes. Topic 3 - Crude Oil. Topic 4 - Synthetic Polymers. Topic 5 - Ethanol Separate Sciences only. Year 11 Prep Book. Year 11 Revision Checklist. You can find a booklet of past paper questions and the examination board's answers by clicking a link below. Past Paper Questions by topic You can find a booklet of past paper questions and the examination board's answers by clicking a link below.Multiple choice questions appear throughout both exam papers and at both Foundation tier and Higher tier.
Multiple choice questions are usually asked as questions, often starting with 'what is You have four options to choose from in a multiple choice question.
You must only chose one of these options, by placing a tick or cross in a box. You will not get a mark if you leave all the boxes blank or if you put a tick or cross in more than one box. A student investigates the rate of reaction between zinc and excess dilute hydrochloric acid. The table shows his results. What is the mean rate of reaction in the first 20 seconds in cm 3 of hydrogen produced per second? Edexcel question courtesy of Pearson Education Ltd.
Which of these correctly describes energy changes due to reactions in solution? This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.
The decomposition of hydrogen peroxide is catalysed by adding a small amount of manganese IV oxide. Which of these graphs shows the mass of the catalyst as the reaction takes place?
Which of the following correctly describes processes that happen during reactions? Rates of reaction and energy changes - Multiple choice questions Multiple choice questions appear throughout both exam papers and at both Foundation tier and Higher tier. Sample question 1 - Foundation Question A student investigates the rate of reaction between zinc and excess dilute hydrochloric acid.
Time s Volume of hydrogen cm3 0 0 20 42 40 66 60 75 80 80 82 What is the mean rate of reaction in the first 20 seconds in cm 3 of hydrogen produced per second? Reveal answer up.
Endothermic - temperature increases; Exothermic - energy is transferred to the surroundings. Endothermic - temperature decreases; Exothermic - energy is transferred from the surroundings.
Endothermic - energy is transferred to the surroundings; Exothermic - temperature decreases. Endothermic - energy is transferred from the surroundings; Exothermic - temperature increases. Bonds are broken in reactants, which is an exothermic process that takes in energy. Bonds are broken in reactants, which is an endothermic process that gives out energy. Bonds are made in products, which is an endothermic process that takes in energy.Rates of Reaction. The best way to remember the information in this chapter is to get a pen and paper and write down your answers before clicking on the Answer link which will take you to the correct page.
You may have to read through some of the page before you find the answer. If the answer you have written is not rightchange it to the correct answer by copying down the information from the correct page.
All Rights Reserved. Rates of Reaction 1 What does Collision Theory say? Answer 3 Give three ways of Increasing the Rate of a Reaction. Answer 4 How can the Rate of a Reaction be Measured? Answer 9 What happens if you Increase the Temperature? Answer 10 What happens if you Increase the Concentration? Answer 11 What happens if you Increase the Pressure? Answer 12 What happens if you Use a Powder?
Catalysts and Enzymes 13 What is a Catalyst? Answer 14 Give One Example of a Catalyst. Answer 15 What is an Enzyme? Answer 16 When does an Enzyme Denature?
Rates of reaction worksheet - lower ability
Answer 17 When does Lipase do? Answer 18 When does Protease do? Answer 19 Write the Word Equation for Fermentation. Answer 20 Why must Air be Excluded from Fermentation? Answer 21 How can Ethanol be Separated from Water? Answer 22 Give two Uses of Ethanol. Answer 24 What is Yoghurt made from? Answer 25 Why are Enzymes used in Detergents? Answer 26 Why are Enzymes used in Baby Food? Answer 27 Is Fructose Sweeter than Glucose? Answer 28 Why are Enzymes used in Industry?
Energy 29 What does Exothermic mean? Answer 30 Is Breaking Bonds an Exothermic process? Answer 35 Draw and Label a Simple Calorimeter.Note: The letter i n bold is the corr ect ans wer.
Direction: Read the questions carefully and choose the letter of y our answ er. The rate law for a reaction is k[A ][B]. Which one of the following statements is false? The reaction is first order in A. The reaction is second order overall.
As the temperature of a reaction is increased, the rate of the reaction in creases because the. A react ion was found to be zero order in A. Increasing the concentration of A by a factor of 3 will. The rate law of the overall reaction is k[A ][B]. Which of the following will not increase the rate of. The minimum amount of energy needed to start a reaction is called the. When a lit match is touched to the wic k of a candle, the candle begins t o burn.
When the match is removed, the candle continues to burn, the match. Which step of a reaction is the rate -det ermining step? A cata lys t incre ases the rate of a react ion by. Which of the following would NOT increase the rate of reaction. The rate of a chemical reaction can be expressed in. Which of the following are necessary for successful collisions to occur? F a vourable collision g eomet ry. Sufficient kinetic energy.
II and III onl y. Dust particles suspended in the air in side unheated grain elevators can sometim es react. Preparing Documents.During the course of the reaction shown below, reactants A and B are consumed while the concentration of product AB increases. The reaction rate can be determined by measuring how fast the concentration of A or B decreases, or by how fast the concentration of AB increases.
Not all variables are needed to solve for the rate. Therefore, if you have the value for "A" as well as the value for "a" you can solve for the reaction rate. The reason for this is because the reactants are decreasing as a function of time, the rate would come out to be negative because it is the reverse rate.
GCSE and IGCSE Rates of Reactions
Therefore, putting a negative sign in front of the variable will allow for the solution to be a positive rate. Chemical reactions vary greatly in the speed at which they occur.
Some are ultrafast, while others may take millions of years to reach equilibrium. The Reaction Rate for a given chemical reaction is the measure of the change in concentration of the reactants or the change in concentration of the products per unit time. The speed of a chemical reaction may be defined as the change in concentration of a substance divided by the time interval during which this change is observed:.
Notice the minus signs in the first two examples above. Since negative rates do not make much sense, rates expressed in terms of a reactant concentration are always preceded by a minus sign to make the rate come out positive.
Comment : Because of the way this question is formulated, it would be acceptable to express this last value as a negative number. Most reactions slow down as the reactants are consumed. Note: Instantaneous rates are also known as differential rates.
Thus for the reaction whose progress is plotted here, the actual rate as measured by the increasing concentration of product varies continuously, being greatest at time zero. The instantaneous rate of a reaction is given by the slope of a tangent to the concentration-vs.
Rate Of Reaction
As we shall soon see, initial rates play an important role in the study of reaction kinetics. If you have studied differential calculusyou will know that these tangent slopes are derivatives whose values can very at each point on the curve, so that these instantaneous rates are really limiting rates defined as.
A rate law is an expression which relates that rate of a reaction to the rate constant and the concentrations of the reactants. The general rate law is usually expressed as:. However, there are also other factors that can influence the rate of reaction.A quiz to assess your understanding of the whole topic. A catalyst increases the speed of a reaction by lowering the enthalpy change of a chemical reaction.
Experiment I: 75 cm3 of 1. Experiment I: 75 cm3 of 0. Experiment I: 25 cm3 of 1. Experiment I: cm3 of 1. Forgot your password?
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Questions and Answers. Remove Excerpt. Removing question excerpt is a premium feature. When solid sodium thiosulfate reacts with dilute HCl, sulfur and sulfur dioxide gas are produced. Which of the following cannot alter the rate of this reaction? Which of the following acids will produce the fastest initial speed of reaction when 1. Assume that the experiments are carried out at the same temperature. The mass of a catalyst before and after a chemical reaction is the same. Copper II oxide is a black solid.
It catalyses the decomposition of hydrogen peroxide.