What is the empirical formula of this compound of aluminium and oxygen given:

Al 52.9%, O 47.1%

Write answer as 0 _ _ 0 where the blanks are filled by the empirical ratio of Al and O.

(a)  

Add the

% by mass of O in calcium hydroxide to the

% by mass of N in ammonium iodide doing calculations to 3 sig fig

Now round the answer to 2 sig fig

and precede by a 0

eg 0 1 1

(a)  

5.95 g of hydrated cobalt(II) chloride decomposes to form 3.25 g of anhydrous cobalt(II) chloride on heating.

Calculate the formula mass of hydrated cobalt(II) chloride and the value of n.

CoCl2.nH2O → CoCl2 + nH2O

Input answer as 0 followed by ratio of CoCl2 to water (1 : n)

Eg 0 1 n

(a)  

Calculate the mass of oxygen needed to react completely with 6340 g of calcium to form calcium oxide.

2Ca + O2 → 2CaO

Write answer as 4 significant figures

eg _ _ _ _

(a)  

Find the volume of oxygen gas that reacts with 0.16 dm3 of sulfur dioxide gas measured at room temperature and pressure – rtp

(Molar volume is 24dm3 at rtp)

2SO2(g) + O2(g) 2SO3(g)

Give answer in dm3, include any leading zeroes but ignore decimal points in code input

Eg 12.34 would be 1 2 3 4

(a)  

Chromium is a useful metal. It is extracted from chromium oxide by reaction with aluminium.

Cr2O3 + 2 Al → 2 Cr + Al2O3

First calculate the mass of chromium that can be formed from 1.250 kg of chromium oxide.

If we actually get 690.2 g of chromium, what is the %yield to 3 sig fig?

Ignore any decimal points when inputting code

(a)  

What is the burette reading someone might record down at the beginning of the titration if they fill the burette to the top and the meniscus is sitting on the first line?

Ignore decimal places in inputting code

Input _ _ _ _

(a)  

Find the volume of CO2 gas formed

(at room temperature and pressure)

when 4.493 kg of propane burns in oxygen. Answer to 4dp in dm3

Molar volume is 24dm3 at rtp

C3H8(g) + 5O2(g) = 3CO2(g) + 4H2O(l)

(a)  

How many moles of butane do I have if there is 169.708 kg of it in my cylinder?

Please give your answer to 4 significant figures

Eg _ _ _ _

(a)  

a NO + b H2O + c O2 → d HNO3

The input code is taken from the coefficients in the balanced equation. Balance the equation to get values for a,b,c and d and get the code

Eg a b c d

(a)  

So what is the message? For 0 just leave a space!

(a)