3.4 - Atmosphere & acids Flashcards
what four gases is air composed of
nitrogen
oxygen
argon
carbon dioxide
how much nitrogen is in air
78%
how much oxygen is in air
21%
how much argon is in air
0.96%
how much carbon dioxide is in air
0.04%
how do you measure the percentage of oxygen in air
by reacting it with another element - often a metal
the air gradually decreases in volume until all of the oxygen has been added to the metal
what element might you heat to measure the percentage of oxygen
copper to form copper oxide
how do you calculate the percentage of O2 in air
decrease in volume / initial volume of air x 100 = (should be 21)
why might the air in one of the percentage oxygen experiment not decrease by 21%
- the metal wasn’t heated for long enough for all the oxygen to be reacted
- there’s a leak in the apparatus
what is element combustion
when an element reacts with oxygen to produce an oxide
what is the word equation for element combustion
element + oxygen –> element oxide
what is the oxide name of a metal
metal oxide
what state is a metal oxide
solid
what is the oxide name of a non-metal
non-metal dioxide
what state is a non-metal dioxide
gas
what does magnesium combust to form
magnesium oxide
what is the word equation for the combustion of magnesium
magnesium + oxygen –> magnesium oxide
what is the chemical equation for the combustion of magnesium
2Mg(s) + O2(g) –> 2MgO(s)
what are the observations of the combustion of magnesium
bright white light
white powder formed
what does sulphur combust to form
sulphur dioxide
what is the word equation for the combustion of sulphur
sulphur + oxygen –> sulphur dioxide
what is the chemical equation for the combustion of sulphur
S(s) + O2(g) –> SO2(g)
what is an observation of the combustion of sulphur
blue flame
what does hydrogen combust to form
water
what is the word equation for the combustion of hydrogen
hydrogen + oxygen –> water
what is the chemical equation for the combustion of hydrogen
2H2(g) + O2(g) –> 2H2O(l)
what is an observation of the combustion of hydrogen
squeaky pop
what is the ion formula of Iron(II)
Fe 2+
what is the ion formula of Iron(III)
Fe 3+
what is the ion formula of Copper
Cu 2+
what is the ion formula of Silver
Ag+
what is the ion formula of Zinc
Zn 2+
what is the ion formula of Lead
Pb 2+
what is the chemical test for oxygen
glowing splint - relights
because the oxygen allows the wood in the splint to combust more efficiently
what solutions do metal oxides form when dissolved in water
alkaline
what solutions do non-metal dioxides form when dissolved in water
acidic
how can you determine whether an unknown element is a metal or non-metal
1- combust it in oxygen
2- dissolve the oxide formed
3- check the pH of the solution with an indicator
what is an acid
H+ donor
what is a base
H+ acceptor
what is an alkali
OH- donor