Chemistry (1)

Question 1

how are salts created?

Answer 1

acid + base (neutralisation) -> salts (ionic compounds)

Question 2

how to identify a base?

Answer 2

hydroxides / metal oxides/hydroxides, ammonia

Question 3

explain how to produce anhydrous and hydrated salts?

Answer 3

when making salts, during crystalisation, some water gets trapped in the structure when turning into a solid. ergo, salt with water -> hydrated salt, blue color. you heat up the salt, the water separates and turns back into anhydrous salts. (white)

Question 4

what can be used to test for the presence of water?

Answer 4

copper sulfate

Question 5

what is a colorless and toxic gas?

Answer 5

carbon monoxide poisoning -> cars, people can’t smell or see it, ergo ! carbon monoxide.

Question 6

what are the reactants of fermentation?

Answer 6

generally, it differs based off the TYPE of fermentation, like yeast or alcohol, but glucose is the reactant common in both.

Question 7

how is iron extracted?

Answer 7

three primary stuff used in the blast furnace: hematite (Fe2O3), coke (pure carbon), limestone (calcium carbonate). zone 1: coke burns in air (oxygen) producing carbon dioxide.
zone 2: carbon dioxide is reduced to carbon monoxide by coke.
zone 3: carbon monoxide reduces hematite to iron and carbon dioxide.
calcium carbonate thermally decomposes to calcium oxide + carbon dioxide
the impurity of iron is silicon dioxide, calcium oxide + silicon dioxide -> calcium silicate; this melts off and can be collected as slag.

Question 8

what’s a reducing agent?

Answer 8

reducing agent, reduced agent!

Question 9

what are the composition of dry, clean air?

Answer 9

21-oxygen, 78-nitrogen, 0.4-carbon dioxide

Question 10

what defines an element’s chemical properties?

Answer 10

same number of valence electrons (outer shell electrons)

Question 11

explain the haber process?

Answer 11

H2 and N2 are obtained from natural gases or air respectively and pumped into a compressor, the gases are compressed by 200 atm, the pressurised gas is pumped into a tank containing catylitic iron beds at a 450 celsius. The nitrogen and hydrogen react to form ammonia. the products, ammonia, unused hydrogen and ammonia is pumped into the cooling tank. the ammonia is liquified and removed whilst the unreacted hydrogen and nitrogen are reused.

Question 12

write the equation for the chemical reaction producing ammonia.

Answer 12

N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

Question 13

why are bases ‘proton acceptors’?

Answer 13

because acids contain H+, hydrogen by itself has 1 electron, by H+ indicates that the hydrogen has lost it’s electron, leaving it only as a hydrogen with proton, ergo: it’s technically a proton. during chemical reactions between acids and bases, bases accept the ‘proton’, which basically means the acids bind with the positively charged hydrogen.

Question 14

define a catalyst

Answer 14

a substance that speeds up the rate of reaction while remaning unchanged/unaffected.

Question 15

explain how will I know if the backward reaction of an equation is endothermic or exothermic?

Answer 15

Le chartlier’s principle states that when there’s a change made to an equilibrium reaction, the systerm opposes it. so when you increase the temperature of a reaction, and the products produced are from the reactant side, you’ll be able to identify that the backward reaction is endothermic since, increase in temp -> endo.

Question 16

what happens if I decrease the pressure of an equilbrium reaction, which side does the equilibrium shift to?

Answer 16

based off Le chartlier’s principle, a system counteracts any change by opposing it. Ergo, decreasing pressure forces the equilbrium to shift to the side with more gas molecules in an attemp to increase pressure.

Question 17

State the addition reactions

Answer 17

1) alkene + simple molecule (like bromide) -> di…
2) alkene + hydrogen (hydrogenation) -> alkane, 150c and nickel as catalyst
3) alkene + water (hydration) -> alcohol, 300c and phosphoric acid as catalyst H3PO4, 60 atm

Question 18

How to prepare a preciptation reaction?

Answer 18

add two different soluble salts (lead nitrate and potassium sulfate) into a beaker of water, and mix with a stirring a rod. the salts dissociate in water, the cations from the two different salts react with the anions. ergo, producing a mixture of salts. fliter to remove the insoluble salts, then wash the precipitate with distilled water to remove remnants from the solution. dry the precipitate in an evaporating dish in an oven.

Question 19

What’s a substitution reaction? and state an example

Answer 19

occurs when alkane reacts with a halogen under the presence of ultraviolet radiation.
e.x methane + Chlorine -> Chloromethane + Hydrogen Chloride