Chemical Reactions

Question 1

what salts are soluble in water

Answer 1

sodium, potassium, ammonium & nitrate

most chloride, bromide, iodide except those containing (Ag+, Hg2+, Pb+)

Question 2

what is the chemical formula for methane

Answer 2

CH4

Question 3

what are the charges for this compound:

Cr2O7^2-

Answer 3

O has 7*-2 = 14, but needs to get an overall charge of 2- so Cr must have a charge of 12. 12/2 = 6 so the charge on Cr is 6

Question 4

how is an acid represented in terms of H

Answer 4

H+ donor

Question 5

how is a base represented in terms of H

Answer 5

H+ acceptor

Question 6

what is the conjugate acid of H2O

Answer 6

H3O+ / hydronium

Question 7

what is a conjugate acid-base pair

Answer 7

2 species related to each other by 1H+ (one is a base and the other is an acid). anything that donates an H+ is the acid

Question 8

what is titration

Answer 8

procedure to determine concentration of solution

Question 9

what happens if during titration, the next drop creates colour in the solution

Answer 9

endpoint of titration, there are now extra molecules of the base and they don’t have any acid left to react with

Question 10

how do we know whether the rate of a reaction is 1st, 2nd or 3rd order

Answer 10

the changes of each order are linear (change is constant at every time increment)

Question 11

what is enthalpy

Answer 11

the energy required to change between 2 states

Question 12

explain electrophile/nucliophile

Answer 12

an electrophile has an electron poor site & can form bonds by accepting a pair of electrons from an electron rich site e.g. a nucleophile. most of the time nucleophiles are -vely charged & electrophiles are +vely charged

Question 13

what is a critical temperature

Answer 13

the temperature of a substance above which it can’t exist as a liquid