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Hint
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Answer
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what is an alloy
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substance made of 2 or more different elements where at least 1 is a metal
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what happens when hydrogen is exposed to air
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it reacts with oxygen in the air explosively, producing water, with lots of hydrogen it can be dangerous, burns with an orangy yellow flame and burns very easily.
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why is aluminium used in pots and pans
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strong when alloyed, good conductor of heat and electricity, low density
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what does ductile mean
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a metal that can be drawn into a thin wire
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why do we do titrations multiple times
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do get a specific and accurate result. first time is an approximate, but the times after is more careful as we want a very specific answer.
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how does galvanising work
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galvanising is a combination of coatings and sacrificial protection, first a more reactive metal is sprayed onto the protected metal. this initially acts as a coating, but when the coating is damaged, the protected metal still doesn't corrode as now the coating acts as a sacrificial method as it is more reactive.
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how do you test for ammonia
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use damp, red litmus paper, this turns blue in the presence of ammonia gas, it also has a strong smell
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what metals can react with acid
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metals above hydrogen in reactivity series
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name the 5 group 7 elements in order of reactivity
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astatine, iodine, bromine, chlorine, fluorine
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how do you test for sulfate ions
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add hydrochloric acid to remove impurities. add barium chloride, if sulfate ions (SO4 2-) are present then a white precipitate of barium sulfate will form.
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what is thermal decomposition
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the breaking down of a substance using heat
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state word equation for reaction between calcium carbonate and sulfuric acid
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calcium carbonate + sulfuric acid -----> calcium sulfate + water + carbon dioxide
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are chlorides soluble
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yes, except silver chloride and lead (ii) chloride
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describe the experiment to find the percentage of oxygen in the air using phosphorus
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2 ways: 1st way do same experiment like with copper but just replace copper with phosphorus
2nd way First light phosphorus with a hot wire, phosphorus is very reactive with oxygen but not water. Phosphorus is put on an evaporating dish and floats in the water, a bell jar is placed on top of it and then a bung is put on it. The water level will rise as phosphorus pentoxide is produced and the water rises up to fill the volume of oxygen lost. Record the initial water level and leave it until it is constant. Record the end water level, you will notice that if you subtract the final volume by the initial volume and divide by the initial volume then multiply by 100, we get about 20%. So the phosphorus reacts with the oxygen to produce a phosphorus oxide called phosphorus pentoxide ( C4H10 ). This reaction emits lots of light. |
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what is air made of
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78% nitrogen 21% oxygen 0.9% argon 0.04% carbon dioxide 0.4% water vapour (this is an average across all climates) |
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what are alkalis called
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proton acceptors as they accept H+ ions
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why is an alloy stronger than a pure metal
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because an alloy has different elements with different sized ions which ruins the regular lattice arrangement of a pure metal. pure metals have a regular lattice arrangement so their layers can slide over each other, but alloys don't have this arrangement so their layers cannot slide over one another as easily.
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why is copper used in water pipes
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unreactive, malleable
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what state is bromine at room temperature
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reddish brown liquid
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what metals can react with water
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metals above zinc in reactivity series
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what ions do bases contain
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OH- ions ( hydroxide ions)
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what do metal carbonates thermally decompose into
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carbon dioxide and a metal oxide
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an indicator turned blue in alkali, name the indicator
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litmus paper
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what is a sulfate ion
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SO4 2-
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why does melting point decrease down group 1
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because the atom radii gets larger meaning the electrostatic forces between the positive nuclei and valence electrons are weakened. This results in it being easier to break as the force is weak. And if it's easy to break, it's easier to melt.
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what trend does group 1 have as you go down the group
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reactivity increases boiling/melting point decreases density/ mass increases |
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properties of low-carbon steel
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easily rusts, strong, malleable
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what state is iodine at room temperature
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dark grey solid
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what are group 7 elements called
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halogens
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what are pure, unreactive metals found in the Earth's crust called
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native metals
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if the salt is soluble, what question would you ask to find out what method you should use
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is the salt a potassium or sodium one
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first element in group 1
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lithium
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what is the result of the greenhouse effect
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global warming
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why is a H+ ion considered a proton
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a proton has a 1+ charge. a hydrogen atom has 1 proton and 1 electron. if it loses this electron to become H+, it will obviously just be a single proton.
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what does inert mean
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unreactive
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what state is astatine at room temperature
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black solid
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are hydroxides soluble
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no, except sodium hydroxide, potassium hydroxide and calcium hydroxide ( limewater)
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what is reactivity
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how easily an atom loses or gains electrons
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how do you test for ammonium ions
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add sodium hydroxide to sample and warm it up. If ammonium ions are present then ammonia gas will form. To test for ammonia gas put damp, red litmus paper near sample, if ammonia gas is present the paper turns blue.
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What is steel an alloy of
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iron, carbon and other substances
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how do you test for oxygen
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use a glowing splint, this re-lights in the presence of oxygen
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when an acid reacts with an alkali what is produced
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salt + water
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when copper carbonate is thermally decomposed, what is produced and what colour are the reactants and products
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copper oxide and carbon dioxide. the copper carbonate is a green powder and when thermally decomposed it turns into copper oxide which is black powder so we can see a colour change.
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why does a higher halogen displace one lower in group
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because it's more reactive
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what is the chemical name for rust
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hydrated iron(iii) oxide
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what's hydrated
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with water
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properties of high-carbon steel
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very strong, very hard, not malleable
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what is a redox reaction
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a reaction containing reduction and oxidation
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where are most metals found
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in the Earth's crust as naturally-occurring ores
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how do we know when a sample is pure
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if it boils or melts over a specific temperature and not a range
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why do pure, unreactive metals naturally exist
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because they can't combine with any other substance as they are too inert
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state the balanced chemical equation for the production of rust
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4Fe + nH20 + 302 -----------> 2Fe2O3 . nH20
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what is air
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a mixture of gases
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what colours will potassium chloride go if you add chlorine, bromine or iodine all separately
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chlorine is the most reactive out of the three. But there is no colour change as chlorine cannot displace itself. Colourless, no colour change.
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what is a salt
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an ionic compound
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how many colours do indicators have to be able to turn
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at least 2
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what is a carbonate
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a compound made of a metal and carbonate ions
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what are acids called
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proton donors as they give away H+ ions
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what is universal indicator
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a mixture of different dyes which change colour in a gradual way over a range of pH.
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what is stainless steel mainly comprised of
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carbon, nickel and chromium
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