Chemistry And maths help...

Question

1.The cel of a concentrated side-cube contains 8X atoms on the cell corner and 6Y atoms on its side.What is the empirical formula of the solid?
A.XY3
B.X2Y3
C.X3Y
D.X2Y4
E.X3Y2



2.A sample of ammonia gas (NH3) is completely decomposed into nitrogen and hydrogen in hot iron fiver.If the total pressure is 866 mm/Hg,what is the partial pressure of gas N2 and H2


A.N2: 217 mmHg H2: 650 mmHg
B.N2: 650 mmHg H2: 217 mmHg
C.N2: 144 mmHg H2: 722 mmHg
D.N2: 722 mmHg H2: 144 mmHg
E:N2=H2=433 mmHg


3.The line equation passing through the cut-point of line 3x+2y=7 and 5x-y=3 and perpendicular to line x+3y-6=0 should be...

A.3x+y+1=0
B.3x-y-1=0
C.3x-y+1=0
D.3x+y-6=0
E.3x+y-6=0

4.If (fog)(x) = 4x^2+8x-3 and g(x)= 2x+4,then f^-1(x) is..

Q4.If the average value of a+3,b-1,c+4 and d+2 is 5, then the average of 2a+6,2b-8,2c-6 and 2d+4 is...

A.10
B.8
C.7.5
D.7
E.6

5.Hydrogen saving is done by producing hydrogen from water with solar energy.The gas produced then burnt as the fuel:2H2 (g)+O2(g)>2H2O (l).The main advantage of hydrogen as fuel is not causing pollution.The biggest disadvantage is gas form of this fuel makes difficult to store compared to liquid or solid.What is the volume of hydrogen on temperature of 25C and 1.00 arm to produce energy that equivalent to energy produced from combustion of one gallon octane (C8H18).Octane density is 2.66 kg/gallon with standard formation enthalpy of 249.9 J/mol.

A.1.09*10^4 L
B.12.9*10^3 L
C.1.09*10^3 L
D.3.41*10^4 L
E.3.41*10^3 L

Answer 1

1. A cubic unit cell will can have atoms, molecules, or ions located on the corners, edges, or sides of the cell. Corner atoms contribute (1/8) of the atom to the cell, edge atoms contribute (1/4), and side (or face) atoms contribute (1/2) atom per cell. If you have 8 atoms of X on the corners, they contribute 8*(1/8) = 1 X atom. The 6 face atoms contribute 6*(1/2) = 3 Y atoms. Therefore, the formula is XY₃.

 

2. To work this problem, you first need a balanced equation: 2 NH₃ → N₂ + 3 H₂

Once the initial concentration, x, of ammonia is decomposed, you will have x mm Hg of N₂ gas and 3x mm Hg H₂ gas. Setting these equal to the total pressure, we get x + 3x = 866. 

Combine like terms: 4x = 866

Divide both sides by 4: x = 216.5

Therefore, the final pressure of N₂ = x = 216.5 mm Hg and the final pressure of H₂ = 3x = 649.5 mm Hg.