Chemistry - Chlorine isotopes

bonkysleuth SG

Chlorine has a relative atomic mass of 35.5 , which is higher than its mass number. Explain.

Ok not sure how to explain this part. Think it has something to do with isotopes but can't remember. Just a summary of the explanation will do. Thanks.

OHSheet SG

ok.

For isotopes of chlorine,

chlorine has isotopes of mass number from the range of 32 to 40 from what i rmber, and out of this range, there are 2 principle stable isotopes, Cl-35 adn Cl-37.Then the values are averaged out...

*note: (35+37)/2 is =36 ..and not 35.5..

the value of Cl is taken to be 35.5 cuz of the compositions of the Cl-35 and Cl-37 isotopes i think. If i rmber, its 20% ++ for one, and 70%++ for another.

Yea, i think my teacher explained it to me b4. hahaah..

bonkysleuth SG

There's this question I remember doing in school which asks me why SO2 levels is higher in the winter compared to summer.

My thinking is that in the winter, there will be snow and this "blocks" the roads and hinder smooth journeys of vehicles. With more traffic congestions, more SO2 produced from car engines? Lol.

OHSheet SG

hehehe.. no idea..

but are you sure its concentrations are higher in winter???

Cause if its concentrations are higher in summer, it is still explainable.

nice attempt! XD

deathmaster SG

There's this question I remember doing in school which asks me why SO2 levels is higher in the winter compared to summer.

My thinking is that in the winter, there will be snow and this "blocks" the roads and hinder smooth journeys of vehicles. With more traffic congestions, more SO2 produced from car engines? Lol.

i think more coal will have to be burnt to generate the amount of heat necessary to warm up people's houses during winter, thus releasing a larger amount of SO2 gases into the atmosphere,as oppose to in summer, where heating is not required.

SBS n SMRT SG

Natural occurance of Chlorine

Cl-35 is 75 % and Cl-37 is 25 %

35 X ( 3/4) + 37 X (1 / 4) = 35.5

bonkysleuth SG

Anyone has any idea what are the products when you react zinc nitrate and aq.ammona? zinc hydroxide and _________ (nitrogen, HNO3)?

UltimaOnline SG

Anyone has any idea what are the products when you react zinc nitrate and aq.ammona? zinc hydroxide and _________ (nitrogen, HNO3)?

Hydrolysis of ammonia yields hyroxide ions via a proton transfer from the Bronsted-Lowry acid water to the Bronsted-Lowry base ammonia. The hydroxide ions are precipitated out as Zn(OH)2(s) when ionic product > solubility product.

NH3(aq) + H2O(l) --> NH4+(aq) + OH-(aq)

OH-(aq) + Zn2+(aq) --> Zn(OH)2(s)

No nitrogen gas nor nitrate(V) ions are generated.

On a related note, nitrate(V) ions are identified by being first reduced by zinc and/or aluminium (which is oxidized to Zn2+ and Al3+), to generate the ammonium cation; thereafter, a proton transfer from the Bronsted-Lowry acid ammonium cation to the Bronsted-Lowry base hydroxide anion yields ammonia; finally, heat is applied to overcome the hydrogen bonds between the ammonia and water molecules, to obtain gaseous ammonia.

The gaseous ammonia undergoes hydrolysis on moist red litmus paper turning it blue due to the presence of hydroxide ions generated : NH3(aq) + H2O(l) --> NH4+(aq) + OH-(aq)