HYDROGEN, OXYGEN, THE ATMOSPHERE, POLLUTION Flashcards
what is the word equation for metal + water (steam- for unreactive metals)
metal + water -> metal oxide + hydrogen
what is the word equation for metal + water with ( K, Na, Ca )
metal + water -> metal hydroxide + hydrogen
describe the observations with potassium + water
- it floats and fizzes
- moves around on the surface of the water
- melts into a silver ball
- it catches fire and burns with a lilac flame
- it eventually gets smaller and disapears
- it is a very violent reaction
- when universal indicator is added, the solution turns blue/black indicating that a string alkali has been produced.
what is the equation (word and chemical) for potassium + water
potassium (s) + water (l) -> potassium hydroxide (aq) + hydrogen (g)
K + H2O -> KOH + 1/2H2
is potassium + water a useful method for preparing hydrogen
no, because the reaction was too violent and hard to contain
describe the observations for sodium and cold water
- it floats
- it moves around on the surface of the water
- it fizzes
- melts into a silvery ball
what is the word and chemical equation for sodium and water
sodium (s) + water (l) -> sodium hydroxide (aq) + hydrogen(g)
2Na + 2H2O -> 2NaOH + H2
is sodium and water a useful method for preparing hydrogen
no, the metal is too reactive (not as violent as K)
how can you prepare hydrogen
it can be prepared by reacting water or steam with a metal
describe the observations for calcium and cold water
- the calcium sinks and effervesces (bubbles and fizzes)
- it fizzes and gas bubles are produced and the gas is collected at the top of the test tube.
- the calcium bobs up and down
- a white suspension of calcium hydroxide is seen and the water gets warm
- it is a good way of collecting hydrogen
what is the word and chemical equation for calcium and water
calcium (s) + water (l) -> calcium hydroxide(aq) + hydrogen(g)
Ca + 2H2O -> Ca(OH)2 + H2
describe the observations for magnesium and steam
- the magnesium burns with a bright white light
- a white ash (solid) remains (MgO)
- a colourless gas is collected
describe the observations for magnesium and cold water
the magnesium sinks, it is a very slow reaction and would take a week to collect half a test tube of hydrogen
what is the word and chemical equation for magnesium and water (g)
magnesium + water (g) -> magnesium oxide + hydrogen
Mg (s) + H2O(g) -> MgO + H2(g)
describe how aluminium reacts with water
aluminium cannot react with hot or cold water
aluminium foil does not react with steam - it has an oxide layer of the surface however, if this layer is removed it will then react
powdered aluminium reacts with steam when heated to red heat
what is the word and chemical equation for aluminium and steam
aluminium + steam -> aluminium oxide + hydrogen
2Al(s) + 3H2O(g) -> AlO3 + 3H2(g)
describe how zinc reacts with water
zinc cannot react with react with hot or cold water
zinc can react when it’s heated with steam
what is the word and chemical equation for since and steam
Zinc(s) + water (g) -> zinc oxide(s) + hydrogen(g)
Zn + H2O -> ZnO + H2
describe the appearance of zinc oxide when it has reacted with steam
it is a yellow coal
describe how iron reacts
iron rusts slowly in the prescence of air and water
it reacts reversible with steam at red heat
what is the word and chemical equation for iron and steam
Iron + water (g) -> iron oxide + hydrogen
3Fe (s) + 4H2O (g) -> FeO4(s) + 4H2(g)
describe the appearance of iron oxide when it has reacted iron with steam
it is a black powder
describe how copper reacts with water and steam
copper does not- it is below hydrogen in the reactivity series so cannot displace the hydrogen from water
(metal + water is a displacement reaction)
when creating hydrogen with a metal describe what must happen for the reaction to work
the reaction is a displacement reaction so the metal must be above hydrogen in the reactivity series for the reaction to work - metal + acid is usually a lot more violent than metal + water
there is also anhydrous copper sulphate which is the catalyst and speeds up the reaction
describe the word equation for metal + acid
metal + acid -> salt + hydrogen
describe salts
an acid in which the hydrogen has been replaced by a metal
metal + sulfuric acid -> ?
metal sulfate + hydrogen
metal + hydrochloric acid -> ?
metal chloride + hydrogen
metal + nitric acid -> ?
metal nitrate + hydrogen
what is a substance which speeds up a reaction but remains chemically unchanged?
a catalyst
what is the word and chemical equation for zinc and sulfuric acid
zinc + sulfuric acid -> zinc sulfate + hydrogen
Zn (s) + H2SO4 (aq) -> ZnSO4 (aq) + H2 (g)
describe the observations of potassium and sodium + acid
you don’t - it’s too violent
(both potassium and sodium are very reactive more so than hydrogen)
(both potassium chloride and sodium chloride are soluble)
describe what happens with calcium + hydrochloric acid for making hydrogen
calcium is more reactive than hydrogen
calcium chloride is soluble
it’s very violent but not a dangerous as K and Na
describe what happens with calcium + sulfuric acid
calcium sulfate is insoluble (CaSO4 insoluble)
calcium is more reactive than hydrogen
reaction is very slow (doesn’t really happen at all
describe what happens with copper plus acid to make hydrogen
copper is below hydrogen so won’t react (the salt is insoluble)
describe what happens in the experiment with hydrochloric acid and chromium powder
the powder sinks to the bottom and starts to react with the hydrochloric acid
it effervesces and goes cloudy to blue and then green
hydrogen is given off after using a lit splint and it popped
(chromium is a grey powder and hydrochloric acid is a colourless solution)
chromium is a transition metal and therefore has different valencies the compounds of chromium with different valencies have different colours - v2 = sky blue , v3 = green , v6 = orange/yellow
write the word and chemical equation for chromium and hydrochloric acid
Chromium + Hydrochloric acid -> Chromium chloride + Hydrogen
2Cr (s) + 6HCl (aq) -> 2CrCl3 (aq) + 3H2 (g)
what is the Mr of air
29
how do you collect hydrogen
(over water as hydrogen is insoluble)
|^^^| (1)down ward displace meant of air as H2 is less dense (Mr 2) | | | | | | | | | \ \ |\_\_\_ -----
magnesium + hydrochloric acid
magnesium + hydrochloric acid -> magnesium chloride + hydrogen
Mg (s) + 2HCl(aq) -> MgCl2(aq) + H2(g)
magnesium + nitric acid
magnesium + nitric acid -> magnesium nitrate + hydrogen
aluminium + HCl
aluminium + hydrochloric acid -> aluminium chloride + hydrogen
2Al + 6HCl -> 2AlCl3 + 3H2
aluminium + sulfuric acid
-> aluminium sulfate + hydrogen
2Al + H2SO4 -> Al2(SO4)3
zinc + hydrochloric acid
-> zinc chloride + hydrogen
ZnCl2 + H2
zinc + sulfuric acid
-> zinc sulfate + hydrogen
ZnSO4 + H2
iron + nitric acid
-> iron nitrate (brown solution) + hydrogen
Fe(NO3)2 + H2
iron + sulfuric acid
-> iron sulfate (green solution) + hydrogen
FeSO4 + H2
when burning hydrogen in air wha does it make
combustion
water
in the experiment with burning hydrogen in air- what’s apparatus do you use?
woulfe bottle
u-tube
retort
sink and cold surface in the retort
zinc + dilute sulfuric acid
anhydrous calcium chloride
in the experiment to show hydrogen produces water when burnt in air - what is the purpose of the cold surface in the retort
it’s to condense the water vapour
in the experiment to show hydrogen produces water when burnt in air - what is the purpose of the anhydrous calcium chloride
it is a drying agent- it dries up any excess water from the hydrogen
in the experiment to show hydrogen produces water when burnt in air - how can you show that the liquid collected contains water (chemical test- works with pure or impure water)
add water to the anhydrous copper sulfate powder which is white. it should then turn to hydrous copper sulfate and the powder should them turn blue
CuSO4 + 5H2O -> CuSO4 5H2O
in the experiment to show hydrogen produces water when burnt in air - how can you show that the liquid collected was pure water
boil at 100degrees or freeze at 0degrees
Impure would boil at a much higher temp and would freeze at a lower temperature
what is It called when oxygen is removed
reduction reaction
what is reduction
the removal of oxygen
explain how hydrogen can remove oxygen from certain metal oxides
the removal of oxygen is called reduction so hydrogen is acting as the reducing agent
in the experiment where hydrogen removes the oxygen from metal oxides - what apparatus do you need
porcelain boat (with lead (II) oxide)
Bunsen
hard glass tube
hydrogen and hydrogen flame
explain how hydrogen and lead can switch places in the reactivity series
when it is hot enough, Pb and H switch places on the reactivity series
what is the word and chemical equation with the hydrogen displacing oxygen in metal oxides experiment
hydrogen + lead (II) oxide -> water + lead
H2 + PbO -> H2O + Pb
in the experiment where hydrogen removes the oxygen from metal oxides - why don’t you light the hydrogen at the end of the tube until all the air has been swept out of the apparatus?
The hydrogen would react with the oxygen in the reminding air and set light to the oxygen resulting in your apparatus burning.
in the experiment where hydrogen removes the oxygen from metal oxides - at the end of the experiment, why do we turn off the Bunsen but keep passing hydrogen going over the metal while it cools down?
it could turn back to lead oxide if the air gets back into the tube, so while you let it cool, keep the hydrogen going over it so it stays as just lead
in the experiment where hydrogen removes the oxygen from metal oxides - you repeat experiment and weigh several times until a constant mass is achieved, what is a constant mass?
constant mass is when the mass remains the same (pure lead) after weighing it several times after the experiment.
in the experiment where hydrogen removes the oxygen from metal oxides - which metals oxides can hydrogen reduce
any metals below hydrogen in the periodic table (plus lead if hot enough)
in the experiment where hydrogen removes the oxygen from metal oxides - what are the advantages of using hydrogen rather than a more reactive metal?
a metal oxide reaction is violent
you have to separate the two solids, copper and MgO (if you use a more reactive metal e.g. magnesium)
more reactive metals can be explosive
complete the word and chemical equation
hydrogen+ copper oxide ->
hydrogen+ copper oxide -> water + copper
H2 + CuO -> H2O + Cu
complete the following equation
hydrogen + silver (I) oxide ->
hydrogen + silver (I) oxide -> water + silver
H2 + Ag2O -> H2O + 2Ag
describe the simple test for hydrogen gas
use a burning splint and hold it at the mouth of a test tube containing the gas, if hydrogen is present you will hear a squeaky pop.
in the simple test for hydrogen - why is it important that the splint is held at the mouth of the tube rather than inside the test tube?
there would not be enough oxygen from the air in the test tube for the reaction to take place
what are the uses of hydrogen
- manufacture of ammonia by the Haber process
- hardening of vegetable oils to margarine
- oxy-hydrogen flame welding and cutting
- rocket fuel
describe the manufacture of ammonia (by the Haber process)
(use for hydrogen- NH3) ammonia is used to manufacture fertilisers such a as ammonium sulfate or ammonium nitrate.
1) nitrogen is reacted with hydrogen to make ammonia
in the conditions of:
temp: 450degrees C
pressure: 200atmospheres (200x normal pressure)
catalyst: iron
2) ammonia is then reacted with sulphuric or nitric acid to give ammonium sulfate / nitrate which are used as fertilisers
what is the reaction by the hater process where hydrogen is reacted with nitrogen to make ammonia for fertilisers
N2(g) + 3H2(g) <=> 2NH3(g)
when ammonia is produced from the Haber process to make fertilisers what is it reacted with to make fertilisers
sulfuric or nitric acid
when ammonia is produced from the Haber process to make fertilisers what are the reactions that take place to make fertilisers
2NH3 + H2SO4 -> (NH4)2SO4
NH3 + HNO3 -> NH4NO3
what is combustion
burning in air
how do you identify a salt
salts can be easily identified since they usually consist of positive ions from a metal and negative ions from a non- metal
what percentage of gases are found in air
Nitrogen 78% Oxygen 21% Argon 0.96% Carbon dioxide 0.03% Neon 0.0006%
describe the chemical test for water
add anhydrous copper sulfate (white powder) to water - if water is present then the powder will change to a blue colour
Metal + Acid -> ?
Salt + Hydrogen
Describe the laboratory preparation of oxygen from hydrogen peroxide
When dilute hydrogen peroxide is added (H2O2) is decomposed either by heating or by the use of a catalyst such as manganese oxide MnO2, oxygen is evolved and water is left behind
the equation to show he decomposition of hydrogen peroxide
hydrogen peroxide -> water + oxygen
2H2O2 (aq) -> 2H2O (l) + O2(g)
describe a soluble basic (alkaline) oxide
these oxides dissolve in water to form hydroxides
they react with acids to form salts but don’t react with other alkalis
group 1 and some group 2 oxides are a type of these oxides
describe insoluble basic oxides
these oxides do not dissolve in water
they react with acids to form salts
don’t react with other alkalis
these include some group 2 oxides and transition metals
describe amphoteric oxides
these oxides do not dissolve in water
they react with alkalis to form salts and react with alkalis to form salts with weird names
metals near to the non-metal boarder are of this type e.g zinc or aluminium
describe acidic oxides
these oxides usually dissolve in water to form acids
react with alkalis to form salts but not with other acids
these are usually non-metals
when do salts form
when a metal replaces hydrogen in the acid
what happens when magnesium burns in oxygen
2Mg (s) + O2 -> 2MgO (s)
Magnesium burns with a bright white flame and forms a white ash
magnesium oxide + water ->
2MgO (s) + H2O (l) -> Mg(OH)2 (aq,s)
magnesium hydroxide is PH10 (alkaline)
carbon + oxygen ->
C(s) + O2(g) -> CO2(g)
carbon a black solid burns steadily with a yellow flame to form Carbon Dioxide (colourless flame) or sometimes CO
