Physical Chemistry Answers

The rate of a reaction doubles when the concentration of one of the reactants is

doubled.

In terms of the concentration of this reactant, the reaction is:

What is the third equation for the ionization of fluorine?

An iron wire weighs 2.225g. It’s dissolved in an acid which oxidizes to Fe²⁺ and made up of 250cm^3. A 25cm³ of sample required is 31cm³ of a 0.0185mol L^-1 solution of potassium dichromate in a titration.

1. Calculate the number of moles of potassium dichromate used in the titration?
2. Determine number of moles of iron present in the 250cm³ iron wire solution?
3. Calculate mass of iron present in the iron wire?
4. Calculate percentage of iron present in the iron wire?

An iron weighs 2.225g. It’s dissolved in an acid which oxidizes to Fe²⁺ and made up of 250cm^3. A 25cm³ of sample required is 31cm³ of a 0.0185mol L^-1 solution of potassium dichromate in a titration.

Calculate the number of moles of potassium dichromate used in the titration?

To calculate the entropy change of the system for the combustion of one mole of methane gas at 298K. Standard entropies at 298K are as follows:

S⁰(CO₂)=213.7JK⁻¹

S⁰(H₂O)=69.9JK⁻¹

S⁰(CH₄)=186.3JK⁻¹

S⁰(O₂)=205.1JK⁻¹

Also calculate the entropy change of surroundings if the molar enthalpy of combustion of methane is -8.9×10⁵Jmol⁻¹