Karteikarten
Groups 2 & 7
Karten in diesem Stapel (39)
- 1Describe the trend in reactivity with water of group 2 elementsGoing down the group, reactivity with water increases
- 2Give an equation for the reaction between a group 2 metal and water (using M as any group 2 metal & giving state symbols)M(s) + 2H2O(l) --> M(OH)2(aq) + H2(g)
- 3Give the molecular formula of milk of magnesia, and its real world usesMg(OH)2
Used in indigestion remedies to cure heartburn by neutralising excess stomach acid - 4Give the molecular formula of slaked lime, and its real world usesCa(OH)2
Used to raise the pH of acidic soil - 5Describe the trend in solubility of group 2 hydroxidesGoing down the group, the group 2 hydroxides become more soluble
- 6Describe the physical appearance of group 2 hydroxidesThey are all white solids
- 7Describe the solubility of: 1) Magnesium hydroxide 2) Calcium hydroxide 3) Strontium hydroxide 4) Barium hydroxide1) Almost insoluble
2) Sparingly soluble
3) Quite soluble
4) Dissolves readily to produce a strongly alkaline solution - 8Describe the trend in solubility of group 2 sulfatesGroup 2 sulfates get less soluble going down the group (opposite of hydroxides)
- 9Give a medical use of barium sulfate and explain how this use is possible in terms of solubilityBarium sulfate can be taken by the mouth as a barium meal to outline the gut in medical X-rays because barium sulfate is virtually insoluble
- 10Give an equation for the test for sulfate ions using barium Describe what will be observedBa2+(aq) + SO4-(aq) --> BaSO4(s)
A white precipitate of barium sulfate is formed - 11Why is an acid added in the reaction aboveTo remove any carbonate ions present, making CO2, since white barium carbonate would be indistinguishable from white barium sulfate
- 12Describe the physical appearance of fluorine at room temperaturePale yellow gas
- 13Describe the physical appearance of chlorine at room temperatureGreenish gas
- 14Describe the physical appearance of bromine at room temperatureRed-brown liquid
- 15Describe the physical appearance of iodine at room temperatureBlack solid
- 16Why is the F-F bond so weak compared to the other group 7 molecules?Because the atom is so small that the non-bonding electrons in the outermost shell repel the other non-bonding electrons in the ther fluorine atom as they are so close together
- 17Describe and explain trend in electronegatviity in group 7 elementsElectronegativity decreases going down group 7 as the outer shell of electrons becomes further away from the nucleus, so the attraction to the electrons is weaker, so it attracts electrons in a bond more weakly
- 18Describe and explain the trend in melting & boiling points in group 7 elementsMelting & boiling points increase going down the group because larger atoms have more electrons, so form stronger van der Waals forces between molecules
- 19Describe the trend in oxidising ability of group 7 elementsOxidising ability increases going up the group
- 20Give the products of the reaction between Cl2(g) + 2NaBr(aq)Br2(g) + 2NaCl(aq)
- 21Explain why the reaction above takes placeChlorine is a stronger oxidising agent than bromine, so displaces the bromine in the NaBr bond
- 22Describe & explain the trend in reducing ability of group 7 ionsReducing ability increases going down the group for halide ions because the atoms get larger, so more readily lose an electron
- 23Give the equation for the reaction(s) between sodium chloride and concentrated sulfuric acidNaCl(s) + H2SO4(l) --> NaHSO4(s) + HCl(g)
- 24Explain why the above reaction(s) takes placeIt is an acid base reaction, not a redox reaction, as the chloride ion is too weak a reducing agent to reduce the sulfur in sulfuric acid
- 25Give the equation for the reaction(s) between sodium bromide and concentrated sulfuric acidNaBr(s) + H2SO4(l) --> NaHSO4(s) + HBr
then
2H+ + 2Br- + H2SO4 -> SO2(g) + 2H2O + Br2 - 26Explain why the reaction(s) above takes placeThe first reaction is an acid-base reaction, but then the bromide ions in HBr are strong enough reducing agents to reduce the sulfur in H2SO4 from S6+ to S4+
- 27Give the equation for the reaction(s) between sodium iodide and concentrated sulfuric acidNaI(s) + H2SO4(l) --> NaHSO4(s) + HI(g)
then
8H+ + 8I- + H2SO4 -> H2S + 4H2O + 4I2 - 28Explain why the reaction(s) above take placeThe first reaction once again is an acid base reaction. The second reaction occurs because the iodine ions in HI are very strong reducing agents, so reduce the sulfur from 6+ to 2-
- 29A yellow solid may also be produced in the reaction between potassium iodide and concentrated sulfuric acid. What is this solid?Sulfur
- 30Describe how silver nitrate can be used to test for different metal halidesThe metal halide is added to silver nitrate.
If a F- ions is present, no precipitate will form
If a Cl- ion is present, a white precipitate will form
If a Br- ion is present, a cream precipitate will form
If a I- ion is present, a yellow precipitate will form - 31Why must dilute nitric acid be added to the metal halide before the reaction above can take placeTo get rid of any CO3- or OH- impurities that woud interfere with the test by forming silver carbonate or silver hydroxide precipitates
- 32Other than the colour of the precipitates, how can silver halide molecules be distinguished?Add a few drops of varying concentrations of ammonia solutions
AgCl will dissolve in dilute ammonia
AgBr will dissolve in concentrated ammonia
AgI is insoluble in concentrated ammonia - 33Give an equation for the reaction between chlorine gas and waterCl2(g) + H2O(l) ⇋ HClO(aq) + HCl
- 34What is disporportionation? (link to above reaction)A redox reaction where the oxidation state of some of the atoms of the same element decrease and others increase.
In the above reaction, Cl 0 is oxidised to Cl+ in HClO and reduced to Cl- in HCl - 35Give a real world use for the reaction between water and chlorineThe reaction can be used to purify water for drinking and in swimming pools to prevent disease; chloric acid (HClO) is an oxidising agent and kills bacteria by oxidation.
- 36Give an equation for th reaction between Chlorine gas and water in sunlight2Cl2(g) + 2H2O(l) --> 4HCl(aq) + O2(g)
- 37Give an equation for the reaction between solid sodium chlorate and water (an alternative to direct chlornation of swimming pools)NaClO(s) + H2O(l) ⇋ Na+ + OH- + HClO
- 38Given the above reaction, why are swimming pools kept in slightly acidic conditions?In alkaline solution, the equilibrium moves to the left and the HClO is removed as ClO- ions
- 39Give an equation for the reaction between chlorine gas and cold, dilute sodium hydroxideCl2(g) + 2NaOH(aq) --> NaClO(aq) + NaCl(aq) + H2O(l)