General Chemistry Answers

GivenΔ

Δ

H for the burning of SO₂ in O₂ to form SO₃ is -198kJmol^-1, find the heat released or absorbed when 5g of SO₂ reacts with excess oxygen. (Ans: 16kJ)

A solution containing 121.8 g of Zn(NO3)2 per litre has a density of 1.107 g/mL.

Calculate its molal concentration.

A 560.0 mL of 0.61 M sodium bromide, NaBr solution has a density of 1.046 g mL-1

. Calculate the

molality of the solution.

Hi, can I mix calcium carbonate and bentonite clay together to create a finer bentonite clay mask? Is it OK for the skin?

A mass of 3.₃214 g of sodium bi carbonate was dissolved and and diluted to 250,00 ml of aqueous solution .A 20.550X mL of sodium bicarbonate was used to neutralise 25.00mL of H₂SO₄ solution. Calculate the molar concentration of H₂SO₄ SOLUTION

A 2.545 g of the hydrate copper (II) sulfate with formula CuSO4.xH2O is heated and 63.85 % of the residue is found after heating. Calculate the value of x and the molecular formula of the hydrate compound. (Given the molar mass of hydrate compound is 250.0 g mol-1)

. The following replicate calcium determinations on a blood sample using atomic absorption

spectrophotometry (AAS) and a new colorimetric method were reported. Is there a significant

difference in the precision of the two methods? (04)

AAS

(mg/dL)

Colorimetric

(mg/dL)

10.9 9.2

10.1 10.5

10.6 9.7

11.2 11.5

9.7 11.6

10.0 9.3

10.1

11.2

Why is the pH value for 0.1 mol dm-3 nitric acid, HNO3, different from the pH value for 0.1 mol dm–3 oxalic acid, H2C2O4?