elements from the sea

Question 1

describe reasons why a titration may not be accurate?

Answer 1

• contaminated apparatus
• titre not read at meniscus
• repeats not done

Question 2

name a reason why a sodium-thiosulfate titration may not work

Answer 2

starch indicator added too quickly

Question 3

how do you make a hydrogen halide using an ionic halide?

Answer 3

add concentrated acid to a solid, concentrated ionic halide

Question 4

why are hydrogen fluoride and hydrogen chloride stable when heated but HBr and HI are not?

Answer 4

decreasing strength of H-X bond

Question 5

what is formed when Hydrogen halides react with ammonia?

Answer 5

ammonium halide

Question 6

what is H2SO4 reduced to in the presence of HBr and HI?

Answer 6

HBr= SO2 
HI= H2S

Question 7

how do you convert a percentage into ppm?

Answer 7

multiply by 10,000

Question 8

when will a metal be formed at the cathode?

Answer 8

if the metal is less reactive than hydrogen

Question 9

when will a halogen be formed at the anode?

Answer 9

when the solution is concentrated and contains a halide

Question 10

what does ROYGBIV mean?

Answer 10

red, orange, yellow, green, blue, indigo, violet