Chemistry Answers

Caffeine is a stimulant found in coffee and has chemical formula C8H10N4O2 . A 100g sample of coffee powder contains 980 mg caffeine. Determine %nitrogen in 42.0 g of coffee powder

Convert 80mL (4.03g) of acetic acid into moles of acetic acid

1. 1.275 liter of saturated silver chloride AgCl contains 0.01892 g of

dissolved AgCl at 25℃. Calculate the Ksp for AgCl.

2/ Balance the redox reaction in a) acidic and b) basic solution.

Fe2+ + Cr2O7 2- -> Fe3+ + Cr3+

3 A sample containing iron is titrated with a 0.025 M potassium

dichromate K2Cr2O7 solution with H3PO4/H2SO4. The titration required

26.74 mL of K2Cr2O7 for 1.45 g sample. What is the percent iron in the

sample? (Use the balanced reaction in #2).

Bondline structure and iupac name of C21H38

A chemist performed this reaction and obtained 45.5 g BaSO4. How much HCI

was also produced?

Molar masses: 233.4 g/mol BaSO4,

36.5 g/mol HCI

A. 9.49 g HCI

C. 5.35 g HCI

B. 388 g HCI

D. 7.12 g HCI

2 Al + 3 CuCl₂ → 2 AICI3 + 3 Cu

Molar masses: 27.0 g/mol Al,

134.5 g/mol CuCl2, 63.5 g/mol Cu

A: How many grams of CuCl₂ are

necessary to consume 10 g Al?

Identify oxidizing agent and reducing agent in the reactions.

1. 2Na₂S₂O₃ + I₂ → Na₂S₄O₆+ 2Nal

2. N₂+ 3H₂ → 2NH₃

3. 2FeCl₃ + H₂S → 2FeCl₂ +S + 2HC1

4. 2 Cr³ + H₂O+ 6CIO₃ → Cr₂O₇² + 6CIO₂ + 2H+

5. 3Mg + N₂ → Mg₃N₂

How many grames of mercury and how many grams of oxygen are formed from 45.5g of HgO?

Assign oxidation numbers to all atoms, tell in each which substance is undergoing oxidation and which reduction

PbO2(s)+ Cl(aq)>PbCl2(s)+ O2(g)

The reaction moves in backward direction, when the ratio of the concentrations of the products & the

reactant is:

* Equal to Kc

* Greater than Kc

* Lesser than Kc

* 10-13