(a)
Choose and explain which element has the greater value for the following properties:
i. electron affinity.
Na or F.
ii. electronegativity.
Cl or Ca.
iii. ionization energy.
S or Se.
iv. atomic radius.
C or Sn.
v. metallic property.
Si or Br.
(b)
Write the electron configurations for the following atoms/ions:
i. Ca.
ii. S.
iii. Mg2+.
iv. O2-.
v. Fe3+.
2.
Lead metal is obtained from lead sulphide through the following reaction:
2PbS(s) + 2C(s) + 3O2(g) → 2Pb(s) +2CO(g) + 2SO2(g)
(a)
If 100g of PbS is reacted with excess C and O2, calculate the mass of lead metal obtained.
(b)
Suppose 100 g of PbS is reacted with 4g of C and 20g O2.
Find the limiting reactant for this reaction.
(c)
For question (b) above, calculate the mass of lead metal obtained.
(d)
If 31.2g Pb is obtained as the yield. calculate the percentage of yield.
(e)
Calculate mass of oxygen is needed to produce 500g of lead metal.
By referring to the chemical equation given, calculate the volume of nitrogen gas in litres, required to react with 40.0 g of magnesium at a pressure of 2.25 atm and a temperature of 15 °C.
3Mg (s) + N2 → Mg3N2 (s)
A nitrogen gas container has a volume of 35.0 L. Calculate the mass of nitrogen in the container if the gas has a pressure of 1800 torr at 42°C.
A gas is initially at volume 40.0 L, pressure 600 mmHg and temperature 35 °C. Calculate the final pressure of the gas in atm if the volume and temperature are changed to 2500 mL and 225 K, respectively.
Calculate the mass of argon gas in 40.0 L at STP
Hi, I have a question that how to increase the melting point of car wax polish? I have made a polish which works great but it is melted at 28 degree Celsius where as it should not melt at as low as 50 degrees so kindly suggest me what I do with the formula, process or what I add to enhance my product's melting point?
Thanks
Find the value for solution with pH=7.0 and pe = 8.0 for the following.
(Fe3+)/(Fe2+) ratio
Find the value for solution with pH=7.0 and pe = 8.0 for the following.
Express the oxidation and reduction half reactions of the following.
(MnO4-+Mn2+) to MnO2(s).