Balance the following reaction of 1.5 M dichromate: Cr₂O₇ ^2– →  Cr³⁺ in acidic solution. 

What is the coefficient on water in the balanced equation?

Balance the following reduction-oxidation reaction in basic solution. What is the coefficient in front of OH^-?

Br_2(l) → BrO₃^-_(aq) + Br^-_(aq)

The following is a redox reaction between potassium and bromine to form potassium bromide:

2 K + Br₂ → 2 KBr

Separate this redox reaction into its component half-reaction.

Identify which of the statements below is true.

Identify the true statement/s from the following statements on the condensed structure and structural formula.

i) The structural formula and condensed structure are just the same. 

ii) A condensed structure only shows the 2D orientation, while the structural formula shows the 3D orientation. 

iii) A condensed structure only shows atoms, while the structural formula shows how the atoms are bonded to one another.

iv) A condensed structure does not explicitly show lone-pair electrons and multiple bonds.

A compound has a molar mass of 84.18 g/mol. Identify the molecular formula of the compound given that the empirical formula is CH₂

Calculate the molar mass of element X if an 83.6-g sample of the compound X₂O₃ contains 39.4 g of oxygen atoms.

Consider the molecular models shown in the figure below (gray = C, white = H, red = O, blue = N, yellow-green = F). Determine the number of moles for Compound I and Compound II if each has a mass of 28.0 grams.

Arrange the compounds below in increasing mass % N

(NH₄)₃PO₄

(NH₄)₂SO₄

(NH₄)₂HPO₄

NaNO₃

NH₄NO₃

NH₃

Iron is obtained from iron(III) oxide. In the following series of reactions, (step 1) hot air (O₂) reacts with coke (C) to produce CO₂ and heat up the blast furnace, (step 2) additional coke reduces CO₂ into CO, and (step 3) the very high temperature allows for CO to reduce Fe in Fe₂O₃.

(Step 1) C (s) + O₂ (g) → CO₂ (g)
(Step 2) CO₂ (g) + C (s) → 2 CO (g)
(Step 3) Fe₂O₃ (s) + 3 CO (g) → 2 Fe (l) + 3 CO₂ (g)

Write mole ratios to show the relationship between reaction components.

Dinitrobenzene is used in making dyes and explosives. Assume that the nitration of nitrobenzene with the aid of a sulfuric acid catalyst and heat proceeds completely to give solely a 1,3-Dinitrobenzene product. If the reaction started with 0.500 mol of nitrobenzene and 0.250 mol of nitric acid, calculate the theoretical yield (in g). 

C₆H₅NO₂ + HNO₃ → C₆H₄(NO₂)₂ + H₂O 

Consider the reaction for the recovery of metallic iron: 

Fe₂O₃ (s) + 3 H₂ (g) → 2 Fe (s) + 3 H₂O (g)

Calculate the percent yield of the reaction of 6.930 g of Fe₂O₃ in excess H₂ if 2.930 g of Fe (s) was produced. The molar mass of Fe₂O₃ is 159.7 g/mol.