Prelim 2015 Chit Chat Thread (7 Viewers)

MilkyCat_ · Aug 22, 2015

In the equation they have the same molar ratio
Number of moles of chalcopyrite=1000000/183.54
=5448.4 moles
Therefore number of moles of copper=5448.4
5448.4=mass of copper/63.55
Therefore mass of copper=346246.05g
=346.25kg

Hope I'm right lol

Ambility · Aug 22, 2015

MilkyCat_ said:
In the equation they have the same molar ratio
Number of moles of chalcopyrite=1000000/183.54
=5448.4 moles
Therefore number of moles of copper=5448.4
5448.4=mass of copper/63.55
Therefore mass of copper=346246.05g
=346.25kg

Hope I'm right lol

That is correct!

Next question! (chemistry again):
Identify the missing products, then balance the equation:
$MgCO_3+HCl\to MgCl_2+X+Y$

DatAtarLyfe · Aug 22, 2015

Sien said:
is parametrics just a year 11 topic or does go deeper into yr 12?

But you need parametrics for conics if u do 4u

DatAtarLyfe · Aug 22, 2015

Ambility said:
That is correct!

Next question! (chemistry again):
Identify the missing products, then balance the equation:
$MgCO_3+HCl\to MgCl_2+X+Y$

$MgCO_3+2HCl\to MgCl_2+H_2O+CO_2$

Next question:

MilkyCat_ · Aug 22, 2015

DatAtarLyfe said:
$MgCO_3+2HCl\to MgCl_2+H_2O+CO_2$

Next question:
View attachment 32313

I didn't know this reaction before now

Sien · Aug 22, 2015

MilkyCat_ said:
I didn't know this reaction before now

It's a rule that with hcl will always have h2o and co2 as products (if I remember correctly )

Ambility · Aug 22, 2015

MilkyCat_ said:
I didn't know this reaction before now

Yeah an acid plus a carbonate always gives salt, water and carbon dioxide.

DatAtarLyfe, I'm working on your question. I can get the first two parts out, but the last one is giving me trouble.

Sien · Aug 22, 2015

What's a fix circle

Sent from my D6503 using Tapatalk

MilkyCat_ · Aug 22, 2015

Sien said:
It's a rule that with hcl will always have h2o and co2 as products (if I remember correctly )

nah because neutralisation reactions

rand_althor · Aug 22, 2015

MilkyCat_ said:
I didn't know this reaction before now

A useful mnemonic is CAWCS: Carbonate + Acid -> Water + Carbon dioxide + Salt

Ambility · Aug 22, 2015

It's getting late, I'm just going to dump my working, tell me if I got close.

$P(2at,at^2)\,\,\,\,\,S(0,a)\,\,\,\,\,t^2:1\\\text{By the division into ratios formula:}\\x=\frac{t^2(0)+1(2at)}{1+t^2}=\frac{2at}{1+t^2}\\y=\frac{t^2(a)+1(at^2)}{1+t^2}=\frac{at^2+at^2}{1+t^2}=\frac{2at^2}{1+t^2}\\\\m=\frac{y_1-y_2}{x_1-x_2}=\frac{\frac{2at^2}{1+t^2}-0}{\frac{2at}{1+t^2}-0}=\frac{2at^2}{2at}=t\\\\t=\frac{y}{x}$

$y=\frac{\frac{2ay^2}{x^2}}{\frac{x^2+y^2}{x^2}}$

$=\frac{2ay^2}{x^2+y^2}\\x^2+y^2=2ay$

So as you can see, I can only get a circle with radius root 2ay. I don't know how you'd get a circle with radius a.

rand_althor · Aug 22, 2015

Ambility said:
So as you can see, I can only get a circle with radius root 2ay. I don't know how you'd get a circle with radius a.

You're pretty close. The radius is a constant term (it doesn't involve y) so it isn't $\sqrt{2ay}$ . What would you do if you were required to change $x^2-4x+y^2=0$ to the general equation of a circle?

Ambility · Aug 22, 2015

rand_althor said:
You're pretty close. The radius is a constant term (it doesn't involve y) so it isn't $\sqrt{2ay}$ . What would you do if you were required to change $x^2-4x+y^2=0$ to the general equation of a circle?

Thank you! I would complete the square!

$x^2+y^2-2ay=0\\x^2+y^2-2ay+a^2=a^2\\x^2+(y-a)^2=a^2$

I guess I better post another question, though I can't be bothered finding one, so I'm making this up on the fly. I believe it is possible.

PHYSICS: A car travelling at 40km/h west collides with a van travelling at 75km/h east. The resultant wreck travels eastbound at 10km/h. If the van's mass was 1500kg, what was the mass of the car?

rand_althor · Aug 23, 2015

Ambility said:
Thank you! I would complete the square!

$x^2+y^2-2ay=0\\x^2+y^2-2ay+a^2=a^2\\x^2+(y-a)^2=a^2$

No worries

. But don't forget the restrictions of the locus. This is question 13 (c) (iii) from the 2014 HSC Extension 1 Paper, so if you can't figure it out have a read of Carrotsticks' solutions (page 10): https://www.dropbox.com/s/zt96vjplroj5xtm/HSC 2014 Extension 1 Solutions.pdf?dl=0

MilkyCat_ · Aug 23, 2015

The feels when you have to study for english

DatAtarLyfe · Aug 23, 2015

MilkyCat_ said:
The feels when you have to study for english

Lol, english is balls

Sien · Aug 23, 2015

How long are your essays usually?

Sent from my D6503 using Tapatalk

Ambility · Aug 23, 2015

Sien said:
How long are your essays usually?

Sent from my D6503 using Tapatalk

800-900 words. I mean you have to write it in 40 minutes, usually.

DatAtarLyfe · Aug 24, 2015

^same about 800. Can go more if i have it prepared beforehand

Graceuf · Aug 24, 2015

Should I be concerned that half of that maths stuff just went over my head?

Although I'm fairly sure we're doing Locus Week 10 after exams.

Prelim 2015 Chit Chat Thread (7 Viewers)

Active Member

Active Member

Booty Connoisseur

Booty Connoisseur

Active Member

将来: NEET

Active Member

将来: NEET

Active Member

Active Member

Active Member

Active Member

Active Member

Active Member

Active Member

Booty Connoisseur

将来: NEET

Active Member

Booty Connoisseur

Member

Users Who Are Viewing This Thread (Users: 0, Guests: 7)