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Chemistry GCSE C4
Chemistry g
Question | Answer |
---|---|
What is an alkali? | It is a base that dissolves in water |
Write the word equation for neutralisation | Acid + base --> salt + water |
What is the reaction of a metal oxide or metal hydroxide with an acid? | Acid + oxide --> salt + water /. Acid + hydroxide --> salt + water |
Carbonates also neutralise to give water and a gas: | Acid + carbonate --> salt + water + carbon dioxide |
What 2 parts is salt made from? | Part acid, part base |
Finish these equations of common acid and base reactions: HCl + NaOH ---> ____ + H2O _____ + CaCO3 ---> CaSO4 + H2O + CO2 2HNO3 + ___ ---> Cu[NO3]2 + H2O 2HCl + CaCO3 ---> CaCl2 + ___ + ___2 | HCl + NaOH ---> NaCl + H2O H2SO4 + CaCO3 ---> CaSO4 + H2O + CO2 2HNO3 + CuO ---> Cu[NO3]2 + H2O 2HCl + CaCO3 ---> CaCl2 + H2O + CO2 |
What type of ions do acid solutions contain ? | Hydrogen ions H+ |
What is universal indicator used for and what are the steps of using it? | It is used to measure the acidity of a solution. First you add a few drops to the test solution and then compare the colour of the solution to a standard colour chart. |
Whats the base needed to make zinc sulphate? | Zinc oxide, zinc hydroxide or zinc carbonate |
Which salt is made when magnesium hydroxide reacts with sulphuric acid? | Magnesium sulphate |
Write a balanced symbol equation for the reaction between HCl and ZnO | ZnO + 2HCl --> ZnCl2 + 2H2O |
Which ions are responsible for making alkaline solutions? | Hydroxide ions OH- |
Work out the relative formula mass of Al(OH)3 | Work inside bracket 16+1= 17 Multiply the bracket 17x3= 51 Work outside bracket =27 Add all together 27+51=78 |
Explain why mass in conserved in a chemical reaction | When chemicals react, the atoms of the reactants swap places to make new compounds, which are the products. They do not disappear. |
What is the formula for working out the percentage yield? | Percentage yield = actual yield / predicted yield x 100 |
Tim made 24g if crystals instead of 32g. What's the percentage yield? | 24 / 32 x 100 = 75% |
How much carbon dioxide is made in the complete thermal decomposition of 59.5g nickel carbonate NiCO3? | ZnCO3 58 + 12 + 16 +16+16 = 118 CO2 12 + 16 + 16 = 44 59.5 / 118 x 44 = 22g CO2 |
Why do farmers use fertilisers? | To increase their crop yields |
What is the formula for finding the percentage of each element in a fertliliser? | Percentage of element = mass of the element in the formula / relative formula mass x 100 |
What's the relative formula mass of ammonium phosphate, (NH4)3PO4? | 149 |
Calculate the percentage of nitrogen in ammonium phosphate | 14 x 3 = 42 42 / 149 x 100 = 28% |
Name three salts (fertilisers) E.g. Acid + base --> salt + water | Nitric acid + potassium hydroxide --> potassium nitrate + water Nitric acid + ammonium hydroxide --> ammonium nitrate + water Sulphuric acid + ammonium hydroxide --> ammonium sulphate + water |
Suggest how a solid example of potassium phosphate could be made. Outline all the main stages | Titrate potassium hydroxide w/ phosphoric acid, using an indicator. Repeat titration until 3 gd results. Use titration result to add correct amount acid and alkali 2gether without indicator. Evaporate most water using hot bath. Crystallise remains, filter |
What is eutrophication? | Waters with very high levels of minerals created by fertiliser pollution, produces a heavy growth of algae. |
What 4 things does the haber process use? | - iron catalyst - high pressure - temperature around 450c - recycling system for unreacted nitrogen and hydrogen |
Why does the Haber process have a high temperature? | Means higher rates but lower yields so it runs at optimum temperature of 450c |
Write the word and symbol equation for the Haber Process | Nitrogen + hydrogen <---> ammonia N2 + 3H2 <---> 2NH3 |
Why is a low pressure not used in the Haber process ? | The yield would be too low |
High pressure gives the highest yields in the Haber process, but it's not Used, why? | Very high pressures are difficult and costly to maintain. A lower, optimum pressure is chosen to give a reasonable yield at a reasonable cost. |
What are the 2 reactants used in making a detergent? | Organic acid and an alkali |
2 reasons why detergents are suitable in cleaning uses | 1. Dissolves grease stains 2. Dissolves in water at the same time |
What does the hydrophobic tail of the detergent dissolve? | Forms bonds with the oil/grease |
What does the hydrophilic tail of the detergent dissolve? | Forms bonds with the water and pulls grease off fabric/dish |
2 reasons why a dry-cleaning method may be used | Fabrics may be damaged by water and grease stains do not dissolve in water but do in dry-cleaning solvent |
What are forces between molecules called? | Intermolecular forces |
Which intermolecular forces are stronger: grease to water or water to water | Water to water |
Whats a batch process? | A process that at the end, a batch of product is made and the reaction stops |
What is continuous process? | It is a process plant which works at Full capacity making ongoing production |
Write down one advantage and one disadvantage of using continuous process | Effective because the plant works at full capacity all the time. Disadvantage- reaction vessels and pipes only designed to work well at one level of output |
What are the 4 reasons why medicines are so expensive? | -Strict safety laws - research and development ( can take many years to develop) - raw materials (may be rare and costly) - labour intensive ( cost of workers, they are made by batch process so less automation is used. ) |
How long can it take to research, develop, test and patent a new drug? | Many years |
What is the use, structure and properties of diamond? | Use- cutting tools, it is very hard. Jewellery, it is lustrous Structure - tetrahedral Properties- doesnt conduct electricity because it has no free electrons, high melting points because of the many strong covalent bonds |
What is the use, structure and properties of graphite? | Use- pencil leads, slippery. Lubricants, slippery Structure - Hexagonal Properties- conducts electricity because of delocalised ions, slippery because layers of carbon atoms are weakly held together and can slide over each other. |
What is the use, structure and properties of buck minster fullerene? | Use- industrial catalyst, nanotubes ( semiconductors in electrical circuits or reinforce graphite in tennis rackets) Structure- sphere Properties- nanotubes have large surface area so can be used as cabs to trap other molecules |
Different forms of the same element are called.... | Allotropes |
Explain why graphite can conduct electricity but diamond can't | Graphite has delocalised electrons that can move about the structure |
The shape of the individual particles - balls or tubes, sieves or cages - is their......a) giant structure b) covalent bond c) nano structure | c) nano structure |
What are the three main stages in water purification? | Sedimentation Filtration Chlorination |
Explain why each stage is used in the purification process? | Sedimentation - (of particles) so the larger bits drop to the bottom Filtration- ( of very fine particles) sand is used to filter out the finer particles that do not sediment out Chlorination- to kill the microbes |
Explain why distillation uses large amounts of energy | The water needs to be heated to boiling point then cooled down. |
Why does producing tap water increase the climate change? | It takes energy to to pump and purify it. |
Water is a .... a) renewable source b) non-renewable source | a) renewable |
What type of reaction takes place between barium chloride and sulphates? | Precipitation |
In a precipitation reaction, how many solutions react to form a solid that doesnt dissolve? | Two |
Write a balanced symbol equation for the reaction between silver nitrate solution and magnesium chloride, MgBr2. | 2AgNO3(aq) + MgBr2(aq) ---> 2AgBr(s) + Mg(NO3)2(aq) |