The diagram represents an atom of element Z.
Z is not the symbol of the element
Calculate the percentage of nitrogen in ammonium nitrate.
[Mr of NH4NO3 = 80]
One mole of Z contains 6.0 × 1023 atoms.
Calculate the number of electrons in one mole of atoms of element Z.
Give your answer in standard form.
The diagram represents an atom of element Z.
Z is not the symbol of the element
The decomposition of hydrated magnesium sulfate is shown in the equation.
MgSO4.xH2O → MgSO4 + xH2O
At the end of the reaction, the mass of MgSO4 remaining in the tube is 6.0 g.
Use this mass and the results in the table to calculate x in MgSO4.xH2O
[for MgSO4, Mr = 120 for H2O, Mr = 18]
This equation represents the formation of hydrated zinc nitrate in the experiment.
Zn(s) + 2HNO3(aq) + 6H2O(l) → Zn(NO3)2.6H2O(aq) + H2(g)
(i) In another experiment, 9.75 g of zinc is completely reacted with nitric acid.
Show that the maximum possible mass of hydrated zinc nitrate crystals that could be formed is
approximately 45 g.
[for Zn(NO3)2.6H2O, Mr = 297]
The actual yield of hydrated zinc nitrate crystals is 36.4 g.
Calculate the percentage yield of hydrated zinc nitrate crystals.
In this experiment a mass of 4.14 g of metal is formed from 4.46 g of the metal oxide.
(i) Calculate the amount, in moles, of oxygen atoms in the sample of the metal oxide.
The formula of the metal oxide is MO, where M represents the symbol of the metal.
Deduce the amount, in moles, of M in the sample of the metal oxide
Calculate the relative atomic mass of M.
Use the Periodic Table to identify metal M.
An organic compound has the percentage composition by mass
C = 36.36% H = 6.06% F = 57.58%
Show that the empirical formula of the compound is CH2F
The relative molecular mass (Mr) of the compound is 66.
Determine the molecular formula of the compound.
Calculate the mass of CuSO4 formed.
Calculate the mass of water formed
Show that the value of x is approximately 4
[Mr of CuSO4 = 159.5 Mr of H2O = 18]
Magnesium sulfate crystals have the formula MgSO4.xH2O
A student uses this apparatus to heat tube A and collect water of crystallisation in tube B.
The student records the mass of tube B at the start and every minute for 6 minutes.
The table gives the student's results
A scientist uses this apparatus in an experiment to reduce a metal oxide to a metal.
Before heating the mass of the empty tube and the mass of the tube and the metal oxide are recorded.
After heating, the tube is allowed to cool and the mass of the tube and its contents are recorded again.
A student uses this apparatus to find the value of x in the formula CuSO4.xH2O
This is the student's method.
· find the mass of an empty boiling tube
· add hydrated copper(II) sulfate to the tube and record the new mass
· heat the hydrated copper(II) sulfate until it changes colour
· allow the tube to cool and record the mass again
The table shows the student's results.