General Chemistry Answers

Using mold concept, find the concentration of NaOH using 0.10 moldm2 given that the volume of acid used was 12.0cm volume of Base 25cm2

. From the following enthalpy changes, C(s) + O2(g)  CO2(g) ΔH = -393.5 kJ H2(g) + ½ O2(g)  H2O(l) ΔH = -285.8 kJ CH4(g) + 2O2(g)  CO2(g) + 2H2O(l) ΔH = -890.3 kJ calculate the value of ∆Hf for CH4.

The number of moles of a sodium salt (A) is defined as m = ∫01 [1/1+x2 ]dx. Given that the sodium salt (A) reacts with concentrated sulphuric acid in the ratio 2:1 to produce a product B according to the equation

A + H2SO4 → B. Find the mass of the compound B that was produced (RMM of B= 20g/mol)

A. (π/4)g B. (20.5 +π/4)g

C. (5/3)m2 D. (5/2)π

The energy level of hydrogen atom is given by the relationship En = -13.6/n2 , where n is a whole number different from zero and En the energy in eV of level n. The wavelength of a seriesof level n whereby n is the number of decayed nuclei of a radioactive sample over a time period of 1 day with half-life of 12hours and initially number of nuclei 8.

A. 500nm

B. 416.1nm

C. 121.9 nm

D. 487.5nm

If n A of current pass for 2 minutes at the cathode where a group I ion X+ dissociates 0.4moles of A reacts with dil H2SO4 and (n2/2)g of a salt (B) is produced. What quantity of charge was deposited at the cathode (RMM of B=2n)?

A. 2 √(0.2)C

B.2/5C

C. 0.6C

D. 3/8C

E. 9/ √(0.3)C

What is the procedure for obtaining an alkyl group?

A. Removal of a hydrogen atom from an alkane

B. Cyclic transformation

C. Nitration

D. Sulphonation

The pH at 25⁰C of a mixture of 20 ml hydrochloric acid (pH₁=2) with 30 mL of the same acid (pH₂=3) is:

A. 5

B. 2.5

C. 1

D. 2.3

How can a titration determine the molar mass of an unknown compound?

Cal was given a 6.0 mole sample of H3AsO4 that he needed to neutralize by reacting with NaOH solution. How many moles NaOH would Cal need?