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QUESTION 1) A student added 8 mL of 0

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QUESTION 1)

A student added 8 mL of 0.25 M barium chloride solution to 9.95 mL of 0.15 M sodium sulfate solution.

BaCl₂ + Na₂SO₄ → BaSO₄ + 2 NaCl

Calculate the mass of the excess reagent.

QUESTION 2)

Calcium hypochlorite, Ca(ClO)₂, can be used to disinfect drinking water. The concentration of chlorate(l) ions required to disinfect water is about 5.6 x 107^-6 M. Calculate the mass of Calcium hypochlorite, Ca(ClO)₂ in g, that should be added to 1,117 L of water to produce a hypochlorite ion concentration of 5.6 x 10^-6 M.

QUESTION 3)

Nitrogen monoxide, NO(g), can be prepared in the lab using the following chemical reaction:

3Cu(s) + 8HNO₃(aq) → 2NO(g) + 3Cu(NO₃)₂(aq) + 4H₂0(I)

If 7 g of copper metal was added to an aqueous solution containing 2.5 moles of HNO₃, how many moles of NO(g) would be produced, assuming a 100% yield?

QUESTION 4)

Ammonium nitrate decomposes to give dinitrogen monoxide and water as shown in the following reaction:

NH₄NO₃ → N₂0 + 2H₂0

If a 208 g sample of NH₄NO₃ decomposes to give 43 g of N₂O(g), what percent of the original sample remains?

QUESTION 5)

1. If 63 mL of 0.200 M KI(aq) was required to precipitate all of the lead(Il) ions from an aqueous solution of lead(Il) nitrate, how many moles of Pb²⁺ was originally in the solution?

QUESTION 6)

During titration, the following data were collected. A 50.0 mL portion of an HCI solution was titrated with 0.500 M NaOH; 200. mL of the base was required to neutralize the sample. How many grams of HCl are present in 48 mL of this acid solution?

QUESTION 7)

How many moles of Co²⁺ are present in 0.200 L of a 65 solution of Col₂?

QUESTION 8)

Pressurized metal gas cylinders are generally used to store commonly used gases in the laboratory. At times, it can be easier to chemically prepare occasionally used gases. For example, oxygen gas can be prepared by heating KMnO₄(s) according to the following chemical reaction:

2KMnO₄(s) → K₂MnO₄(s) + MnO₂(s) + 0₂(g)

How many grams of KMnO₄ would you need to produce 72 g of O₂? The molar mass of KMnO₄ is 158 g/mol.

QUESTION 9)

Pharmacists sell tablets containing magnesium hydroxide, Mg(OH)₂, to combat indigestion. A student carried out an investigation to find the percentage by mass of Mg(OH)₂ in an indigestion tablet. The student reacted the tablet with dilute hydrochloric acid.

Mg(OH)_2(s) + 2HCl(aq) → MgCl₂(aq) + 2H₂0(I)

The student found that 26.26 mL of 0.5 M HCI was needed to react with the Mg(OH)₂ in a 500 mg tablet. Determine the percentage by mass of Mg(OH)₂ present in the tablet.

QUESTION 10)

An aqueous solution of aluminium chloride can be prepared by the redox reaction between aluminium metal and dilute hydrochloric acid. A student reacts 5.61 g of aluminium completely — with dilute hydrochloric acid (HCl) to form an aqueous solution of aluminium chloride (AICI₃). The equation for this reaction is shown below.

2Al (s) + 6HCI (aq) — 2AICI3 (aq) + 3H₂ (g)

Calculate the volume of hydrogen gas formed, in dm³, at room temperature and pressure. Volume of 1 mole of H₂ = 22.414 dm³

QUESTION 11)

Silicon can be made by heating silicon tetrachloride, SiCl4, with Zn.

SiCl4+ 2Zn —Si + 2ZnCl2

24.9 g of SiCl4 is reacted with an excess of zinc. The percentage yield of silicon is 85%. What is the mass of Si made?

QUESTION 12)

Sodium reacts with water as shown below.

2Na (s) + 2H20 (I) → 2NaOH (aq) + H2 (g)

Calculate the mass of sodium in grams that reacts with water to produce 1,589.35 cm³ of hydrogen gas at RTP? (1 mol H₂ = 22414 cm³)

QUESTION 13)

A solution of magnesium nitrate can be prepared by reacting magnesium carbonate, MgCO3, with nitric acid, HNO3(aq). The equation is shown below.

MgCO3 (s) + 2HNO3 (aq) → Mg(NO3)2 (aq) + H20 (I) + CO₂ (g)

Calculate the minimum volume, in mL, of 1.75 M HNO3 that is needed to prepare a solution containing 49.53 g of Mg(NO3)2.

QUESTION 14)

The student plans to add magnesium to 66 mL of 2M H3PO4.

3Mg + 2H3P04 → Mg3(PO4)2+ 3H2

Calculate the mass of magnesium in g, that the student should add to react exactly with the phosphoric acid (H3PO4).

QUESTION 15)

Phosphorus pentachloride (PCl5) reacts with water to form hydrochloric acid (HCI) and phosphoric acid (H3PO4). How many total moles of acids are formed when starting with 10.31 g of PCl5 and excess H20?

PCl5 + 4H20 — 5HCI + H3PO4