||Homework Help||Kindergarten-University. - Page 51

I really need help with this chemistry stuff, my class and I had a sub for the whole week, and we started the chapter Stoichiometry, and he never gave us any proper notes on it and never explained how to do anything at all, it was so bad, so if anyone can help me with this sheet, that would be so much appreciated. P.S chapter before this one was the Mole concept, and had a sub for that too, and I really sucked at balancing stuff.

http://imageshack.us/f/221/scan0004gy.jpg/

@Ayeshaa
1)(a) The balanced equation is
2Al2O3 + 3C ------> 4Al + 3CO2

2 moles Al2O3 react with 3 moles of carbon
Therefore 43 moles Al2O3 react with
(3/2) * 43 = 64.5 moles carbon
Ans: 64.5 moles

(b) 3 moles C react with 2 moles Al2O3
Therefore 17.8 moles C react with
(2/3) * 17.8 = 11.87 moles Al2O3
Molar mass of Al2O3 = 27*2 + 16*3 = 102 g/mol

11.87 moles Al2O3 = 11.87 * 102 = 1210 g
Ans: 1210 g

c) 2.19 x 10^3 g Al2O3 = 2.19 x 10^3/102 = 21.47 mol Al2O3
2 moles Al2O3 react with 3 moles C
Therefore 21.47 moles Al2O3 react with
(3/2) x 21.47 = 32.21 mol C

32.21 mol C = 32.21 x 12 = 386.5 g C
Ans: 386.5 g

d) 760 kg Al = 760 x 10^3 g Al = 760 x 10^3/27 mol = 28148 mol Al
4 moles Al are produced by 2 moles Al2O3
Therefore 28148 mol Al are produced by
(2/4) * 28148 = 14074 mol Al2O3
= 14074 * 102 g Al2O3
= 1,435,548 g Al2O3
= 1436 kg Al2O3 (Answer)

Can you solve the second problem? The balanced equation is
TiCl4 + 4Na ---> 4NaCl + Ti

^ thanks so much for the help, I think I sort of understand it now, I tried doing that Ti problem :

@Miggi

p + rho*g*h1 + 1/2*rho*v1^2 = p + rho*g*h2 + 1/2 * rho*v2^2
rho*g*h1 + 1/2*rho*v1^2 = rho*g*h2 + 1/2 * rho*v2^2
Put v1 = 0
rho*g*h1 = rho*g*h2 + 1/2 * rho*v2^2
Divide by rho
g*h1 = g*h2 + 1/2 * v2^2
v2 = sqrt[2g(h1-h2)]
v2 = sqrt(2 * 9.8 * 0.025)
v2 = 0.7 m/s

Hey akhl thanks for your help

I have one more question

A 0.50kg object , suspended from an ideal spring of spring constant of 25N/m, is oscillating vertically with amplitude of 7.5cm. How much change of kinetic energy occurs while the object moves from the equilibrium point to a point 5.9cmlower?