Chemistry and Biology Question(s)

1. NaCl because Cl- is oxidised on the anode 2Cl- ---> Cl2 + 2e- it is the chlorine that bleaches. H+ is reduced to H2 on the cathode. OH- remaining, so alkali.

2. Don't know what the question is.

Reply 2

capablanca

Concentrated sodium cloride is known as brine. Its electrolisis produce H2 which pops when put near a fire source. Next aques Cl- produce hypoclorate acid which bleach the litmus paper. While Na+ becomes sodium hydroxide which is an alkali.

Reply 3

OP

Yea but it said "Products obtained from the electrolysis". The OH- that remains in the electrolyte is not the product, it's just what remains. The product is Cl2 and H2.

... is it NaOH (according to capablanca) or OH- (according to Eau) that makes the product alkali.. =.=

Reply 4

Excalibur

OH- ion is the thing that makes it an alkaline. So NaOH is the alkali. NaOH counts as a product too, because it wasn't a reactant and it's produced as a result of electrolysis.

Yes, aqueous means it contains water.

I don't know what question 2 is asking.

Reply 5

OP

Answer is B which I have no idea why?!?!?!

and another question

Which metal is used with aqueous sodium hydroxide to test for nitrate ions in solution?

a) Aluminium
b) Copper
c) Magnesium
d) Tin

what's the answer and why? I just know that aluminum, copper and magnesium are used for positive ion test with aq sodium hydroxide..

Reply 6

Effector does not mean where auxin is produced. An effector is the part that responds to stimulus. The stem is responsible for bending the plant - not the leaves.

I don't think you need to know exactly why aluminium is used at this stage (IGCSE?), but I think aluminium reduces NO2 to NH3 in basic conditions. And you could test the ammonia produced with damp red litmus.

Reply 7

OP

Another question, the answer is C which I don't know why :s-smilie:

and thanks for the help guys!

Reply 8

Catchetat

Another question, the answer is C which I don't know why :s-smilie:

and thanks for the help guys!

You want to REMOVE the ink. So obviously, you want to find a solvent which dissolves the ink and carry it away - you can only carry it away if the solvent does not dissolve in the polyester... or else the ink will stay on the polyester. Hope that makes sense.

Solubility can be understood as likability. If the solvent likes both the ink and shirt, then that's not going to resolve anything. But if the solvent likes the ink but not shirt, that it will seduce the ink away from the shirt. Okay just trying to convince my arguement, lol.

Reply 9

OP

why must the solvent not dissolve in the polyester? doesn't really make sense to me o.O i like your explanation about the likeability stuff lol.

hm i donno the answer

i'm not sure about the R bit..

Reply 10

Catchetat

why must the solvent not dissolve in the polyester? doesn't really make sense to me o.O i like your explanation about the likeability stuff lol.

hm i donno the answer

i'm not sure about the R bit..

So are you saying the likability analogy doesn't explain - but you still like it? -_-

Well I tried my best. If the solvent is soluble in the polyester AND the ink, then the solvent will carry the ink and seep into the polyester (v. bad). Whereas if the solvent is insoluble in the polyester, then the solvent will carry the ink, and AWAY from the polyester, because it's insoluble there.

Carbon makes 4 bonds with other atoms... or it will have a positive charge - very unstable...

R would be something like ammonia...

Reply 11

OP

oooh and I sort of get the ink thing :P thanks!

Reply 12

Catchetat

oooh and I sort of get the ink thing :P thanks!

Yay, finally! I feel happy :smile:

- to be able to explain this inky question to you! And no I don't want to be a teacher, lol!

Reply 13

OP

hm another question! element x can form 4 covalent bonds.

does it always mean that element x is a group 4 non-metal?

Reply 14

Catchetat

hm another question! element x can form 4 covalent bonds.

does it always mean that element x is a group 4 non-metal?

Yep. Right on.

Reply 15

OP

ok thanks. Hm why is water a poor conductor of heat? We did the experiment like the ice thing in test tube but I forgot about it... why is water a poor conductor in terms of its structure?

and is glass a poor conductor of heat because it has no free ions due to its giant covalent structure?

Reply 16