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Chemistry Tests- gases

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wuwojuxe's version from 2018-03-07 15:39

Section 1

Question Answer
Oxygencolourless gas/relights a glowing wooden splinter
no effect
Carbon DioxideColourless gas/lime water turns milky
blue to red
Ammoniawhite fumes/ conc hydrochloric acid vapour
red to blue
Nitrogen dioxideBrown gas
blue to red
HydrogenColourless gas / ignites with a pop sound
no effect
Hydrogen Chloridecolourless gas/white fumes with conc ammonia vapour
blue to red
Chlorinegreenish yellow gas/ -
decolourise
Sulphur dioxideColourless gas/ decolourise purple colour of acidified pottasium manganate (VII) solution
blue to red
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Section 2

Question Answer
What forms carbon dioxide on heating?Carbonates of metals other than group 1
What forms oxygen on heating?Group 1 nitrates (except Li)
What forms oxygen and nitrogen dioxide?Nitrates other than (na or K)
What forms water on heating?Hydrated salts
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Section 3

Question Answer
What forms carbon dioxide when dilute HCl or dilute H2so4 is added?carbonates
What forms hydrogen when dilute HCl or dilute H2so4 is added?a metal
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Section 4

Question Answer
What causes a yellow flame?sodium ion
What causes a lilac flame?Potassium ion
What causes a yellow-red flame?Calcium ion
What causes a red flame?Lithium or strontium ion
What causes a pale green flame?Barium ion
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When a dilute sodium hydroxide solution is added to a solution containing a metal ion

Question Answer
What happens when magnesium, barium, strontium or calcium ions are added to a) dilute NaOH b) excess dilute NaOH?a) white precipitate b) Precipitate is insoluble
What happens when sodium or potassium ions are added to dilute NaOH?No precipitate forms
What happens when Ammonium ion is added to dilute NaOH?No precipitate but ammonium forms on warming
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What happens when conc H2SO4 is added to a solid halide

Question Answer
Chloride?Steamy fumes formed, vigorous reaction; HCl formed
Bromide?Steamy fumes, brown vapour, vigorous reaction; HBr, Br2(SO2) formed
Iodide?Steamy fumes, black solid, purple vapour, yellow solid, rotten egg smell, vigorous reaction; HI, I2, S, H2S formed
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Silver nitrate solution to test for halides

Question Answer
What colour does ppt if chlorine is present; what is the formula of the PPt; What happens when dilute/conc NH3(aq) is added?White AgCl ppt; Dilute, ppt is soluble; nothing happens when conc NH3 is added
What colour ppt when bromide is present; what formula; What happens when dilute/conc NH3(aq) is added?Cream AgBr ppt; dilute- soluble in excess- soluble in conc.
What colour ppt when iodine is present; what formula; What happens when dilute/conc NH3(aq) is added?Yellow AgI ppt; insoluble in both dilute and conc NH3
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Barium Chloride solution- test form SO4^2- ion (BaCl(aq) is often used with dilute HCl.

Question Answer
What colour/ formula ppt when sulfate anion is present; what happens when dilute HCl is added?white BaSO4 ppt; insoluble ppt with HCl
What colour/ formula ppt when sulfite anion is present; what happens when dilute HCl is added?White BaSO3 ppt; ppt dissolves with HCl
What colour/ formula ppt when carbonate anion is present; what happens when dilute HCl is added?White BaCO3 ppt; pp dissolves with effervescence with HCl
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Additional Ion tests

Question Answer
what is the test for ammonium NH4+ ion?Add dilute NaOH solution to a solution of the sample; warm mixture gently; test evolved gas with damp red litmus paper- if +ve turns blue (and effervescence)
what is the test for nitrate NO3- ion?Add dilute NaOH solution AND a small piece of aluminium foil or a spatula of Devarda's alloy to a solution of the sample; warm mixture gently; test any gas with damp red litmus- +ve turns damp red litmus blue + effervescence
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Organic Compounds Solubility

Question Answer
What is identity of an organic compund soluble in water? (if pH below 7 what is it)Could be simple alcohgols, simple carboxylic acid, propanone, simple aldehydes- if pH<7 it is a carboxylic acid
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organic compound ignition

Question Answer
What can we draw from a sooty flame?it is aromatic, unsaturated- e.g. alkene
What can we draw from a clean flame?saturated low molar mass compound
What can we draw from a flame with no residuecould be most low molar mass compounds
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Organic Compound Chemical Tests

Question Answer
How to test for primary/ secondary aldehyde; what are the results?Warm solution with acidified potassium dichromate (VI)- orange to green
How to test for alkene; result?Shake with bromine water- yellow solution is decolourised
How to test for halogenoalkanes, what are the results for each halogen?Warm solution with aqueous sodium/ potassium hydroxide, acidify with dilute nitric acud then add aq. silver nitrate: Cl = white ppt; Br= cream ppt; I= yellow ppt
How to test for OH group in alcohol and carboxylic acid(results)?Add phosphorous (V) chloride- steamy HCl fumes form; turn damp blue litmus paper red
How to test for carboxylic acid (result?)Add sodium or potassium carbonate or hydrogencarbonate solution- effervescence occurs
How to test for an alcohol or a carboxylic acid (result?)add a small piece of sodium; effervescence (bubbles), sodium dissolves, white solid is formed
How to test for an alcohol (result)Warm with carboxylic acid and a few drops of conc sulfuric acid; ester smell e.g. glue like
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