The rate of a reaction is a measure of how quickly a reactant is used up, or a product is formed. For a chemical reaction to happen:. A collision that produces a reaction is called a successful collision. The activation energy is the minimum amount of energy needed for a collision to be successful.
It is different for different reactions. Colliding particles. Two pairs of particles move towards each other. The pairs collide and reform so that each member of the original pair joins with a member of the other pair, forming two new pairs. The new pairs are now moving away from each other. There are different ways to determine the rate of a reaction. The method chosen usually depends on the reactants and products involved, and how easy it is to measure changes in them.
The mean rate of reaction can be calculated using either of these two equations:. The change in mass of a reactant or product can be followed during a reaction. This method is useful when carbon dioxide is a product which leaves the reaction container. It is not suitable for hydrogen and other gases with a small relative formula massM r. The change in volume of a reactant or product can be followed during a reaction. This method is useful when a gas leaves the reaction container.
The volume of a gas is measured using a gas syringe, or an upside down burette or measuring cylinder. The units for rate are usually cm 3 s -1 or cm 3 min The rate of reaction can be analysed by plotting a graph of mass or volume of product formed against time.
The graph shows this for two reactions. The gradient of the line is equal to the rate of reaction:. The rate of a chemical reaction can also be measured in Mol s Rate of reaction The rate of a reaction is a measure of how quickly a reactant is used up, or a product is formed. Collision theory For a chemical reaction to happen: reactant particles must collide with each other the particles must have enough energy for them to react A collision that produces a reaction is called a successful collision.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?
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.
Bonds are made in products, which is an exothermic process that gives out energy.A member of The Profs team will be in touch to discuss your tuition plan once you've submitted your details.
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6.1 Rate of Reaction
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Common IGCSE Chemistry Exam Questions With Answers
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This blog includes many of those repeat questions. By keeping these questions in mind, you can easily get quite a lot of marks in your bag. I have also included the answers. I have collected these questions by analyzing over 10 years worth of question papers. But if your IGCSE Chemistry concepts are very weak, it will be difficult for you to make full use of these common question answers.
Hence it might be better if you revise all the IGCSE Chemistry concepts within a short time, like a week or two using a revision guide. Sample Question : Explain, in terms of its structure and bonding, why magnesium oxide has a very high melting point.
Ans: Cracking produces smaller hydrocarbons, smaller hydrocarbons have greater demand, they are easier to burn, and also cracking produces more reactive alkenes.
This is a neutralization reaction. There is attraction between the oppositely charged ions.
Ans: It is the average mass of all the isotopes of an element. The mass of each isotope is in the scale of Carbon Ans: Take a clean nichrome wire, take solid M on the tip of the wire, then using the wire put the solid M in the blue part of the Bunsen burner flame. Sample Question 1: Explain how the covalent bonds in the water molecule hold the hydrogen and oxygen atom together?
Ans: The positive nuclei of both the oxygen and hydrogen atom are attracted towards the shared electron pair.
Sample Question 2: Explain how hydrogen and bromine atoms are held together in a molecule of hydrogen bromide? Ans: The positive nuclei of both the hydrogen and bromine atom is attracted towards the shared electron pair. Sample Question: Explain why water has a much lower melting point than sodium oxide. Ans: There are weak intermolecular attraction between the water molecules, which takes low energy to overcome. Ans: Iron structure has delocalized electrons, which are able to move around and conduct electricity.Car fuel pump fuse keeps going out full version
Ans: A catalyst is a chemical which increases the rate of reaction without getting used up itself. Ans: A catalyst provides an alternative route for the reaction to occur which has less activation energy. Ans: At higher temperature, particles move faster collision frequency increases. More number of particles have higher energy than the activation energy, hence more number of useful collisions occurs. Ans: It is a process in which large hydrocarbons are broken down to smaller hydrocarbons with the help of catalyst or heat.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.Togel keluaran mlm jam 11 brazil
Answer 15 What is an Enzyme? Answer 16 When does an Enzyme Denature? 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. Answer 36 In Calorimetrywhich Variables must be kept Constant? What does Collision Theory say? Give three ways of Increasing the Rate of a Reaction. How can the Rate of a Reaction be Measured?This is done to check for duplicate values for the key value that you are searching for.
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Find information about our open position for assistant professor. Statistical ResourcesFind a listing of the statistical resources you need Department of Statistics Ballantine Hall 643 1020 E Kirkwood Ave Bloomington, IN 47405 Phone: 812. The Yearbook of Immigration Statistics is a compendium of tables that provides data on foreign nationals who were granted lawful permanent residence, were admitted into the United States on a temporary basis, applied for asylum or refugee status, or were naturalized.
A refugee is a person outside his or her country of nationality who is unable or unwilling to return to his or her country of nationality because of persecution or a well-founded fear of persecution. An asylee is a person who meets the definition of refugee and is already present in the United States or is seeking admission at a port of entry.
DHS engages in immigration enforcement actions to prevent unlawful entry into the United States and to apprehend and repatriate aliens who have violated or failed to comply with U. Infographics produced by the Office of Immigration Statistics to make data provide by Department of Homeland Security components more readily available to the public.
The Office of Immigration Statistics (OIS) prepares special reports in response to Presidential, Secretarial, and Congressional directives. In addition to regularly released data, the Office of Immigration Statistics responds to customized tabulations from the public. Below are a collection of tabulations in response to these requests.IGCSE Chemistry: Acids Bases and Salts
Tabulations are organized by topic and each page contains an explanation of what the files contain. White papers and special projects related to immigration which may expand upon concepts in core reporting or topics of special interest to stakeholders. Citizenship and Immigration Services library was created in 1987 as part of the legacy Immigration and Naturalization Service (INS) History Office. Skip to Main Content Official website of the Department of Homeland Security Contact Us Quick Links Site Map A-Z Index Topics How Do I.Pastebin eth private key
Nonimmigrant Admissions Immigration Enforcement Actions Immigration Enforcement Priorities Data Visualization Fact Sheets Population Estimates Special Reports Reading Room Research Library Historical Library Data Standards and Definitions Definition of Terms Geographic Regions Disclosure Policy Frequently Asked Questions (FAQ) Across the AgenciesBureau of Population, Refugees, and Migration (Dept.These measures differ only with regard as to how tied ranks are handled.
In most cases these values will be fairly similar, and when discrepancies occur, it is probably always safest to interpret the lowest value. The Gamma statistic is preferable to Spearman R or Kendall tau when the data contain many tied observations.
Thus, Gamma is basically equivalent to Kendall tau, except that ties are explicitly taken into account. Detailed discussions of the Gamma statistic can be found in Goodman and Kruskal (1954, 1959, 1963, 1972), Siegel (1956), and Siegel and Castellan (1988). Multiple response variables or multiple dichotomies often arise when summarizing survey data. The nature of such variables or factors in a table is best illustrated with examples.
As part of a larger market survey, suppose you asked a sample of consumers to name their three favorite soft drinks. Also, a wide variety of soft drinks will most likely be named. The next question is how to enter the responses into a data file.
Suppose 50 different soft drinks were mentioned among all of the questionnaires. This method of coding the responses would be very tedious and "wasteful.
Alternatively, we could set up three variables, and a coding scheme for the 50 soft drinks. Then we could enter the respective codes (or alpha labels) into the three variables, in the same way that respondents wrote them down in the questionnaire.
To produce a table of the number of respondents by soft drink we would now treat Resp. Note that the counts in the first column of the table do not add up to 500, but rather to 842. For example, referring back to the sample listing of the data file shown above, the first case (Coke, Pepsi, Jolt) "contributes" three times to the frequency table, once to the category Coke, once to the category Pepsi, and once to the category Jolt.
The second and third columns in the table above report the percentages relative to the number of responses (second column) as well as respondents (third column).
Thus, the entry 8. Suppose in the above example we were only interested in Coke, Pepsi, and Sprite. As pointed out earlier, one way to code the data in that case would be as follows: COKE PEPSI SPRITE. In other words, one variable was created for each soft drink, then a value of 1 was entered into the respective variable whenever the respective drink was mentioned by the respective respondent. In a sense, we "compact" the three variables Coke, Pepsi, and Sprite into a single variable (Soft Drink) consisting of multiple dichotomies.
All of these types of variables can then be used in crosstabulation tables.Xcom 2 ranks
For example, we could crosstabulate a multiple dichotomy for Soft Drink (coded as described in the previous paragraph) with a multiple response variable Favorite Fast Foods (with many categories such as Hamburgers, Pizza, etc. As in the frequency table, the percentages and marginal totals in that table can be computed from the total number of respondents as well as the total number of responses.
For example, consider the following hypothetical respondent: Gender Coke Pepsi Sprite Food1 Food2 FEMALE 1 1 FISH PIZZA This female respondent mentioned Coke and Pepsi as her favorite drinks, and Fish and Pizza as her favorite fast foods. In the complete crosstabulation table she will be counted in the following cells of the table: Food. FEMALE MALE COKE PEPSI SPRITE COKE PEPSI SPRITE X X X X 2 2 This female respondent will "contribute" to (i.
Paired Crosstabulation of Multiple Response Variables. A unique option for tabulating multiple response variables is to treat the variables in two or more multiple response variables as matched pairs.
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