ch 8 chemical equations

Balance the unbalanced equation below, using lowest possible whole-number coefficients, then match each substance to the correct coefficient as indicated. Al2S3 (s) + H2O (l) → Al(OH)3 (aq) + H2S (g)

Al2S3 = 1 H2O = 6 Al(OH)3 = 2 H2S = 3

Hydrocarbons are compounds that contain only carbon and hydrogen. Combustion of a sample of a particular hydrocarbon gave 5.86 g of CO2 and 1.37 g of H2O. What is the empirical formula of the hydrocarbon?

C7H8 Reason: 5.86 g CO2 × (12.01g C / 44.01g CO2) × (1mol C / 12.01g C) = 0.133 mol C. 1.37 g H2O × (2.016g H / 18.02g H2O) × (1mol H / 1.008g H) = 0.152 mol H. 0.152/0.133 = 1.14 = 8/7. Hence, C_0.133H_0.152 = C7H8

Correctly place the steps in order for determining the molecular formula of a compound from combustion analysis data, if the approximate molar mass is known

1. Determine the empirical formula of the compound from the combustion analysis data 2. Use the empirical formula to calculate the empirical molar mass 3. Divide the approximate molar mass of the compound by the empirical molar mass, and round the quotient to the nearest integer 4. Multiply each subscripts in the empirical formula by the integer obtained

Correctly order the steps necessary to determine the empirical formula of a compound from combustion analysis data

1. Determine the masses of C and H from the masses of CO2 and H2O 2. Determine the mass of O, if present, by subtracting the masses of C and H from the total mass of the initial sample 3. Determine the number of each element in the compound, and use the results as subscripts in a chemical formula 4. Convert the subscripts in the formula to whole numbers, by dividing each by the smallest subscript

Correctly order the steps used in a combustion analysis experiment to determine the empirical formula of an organic compound.

1. The mass of the original sample is determined by weighing 2. The sample is heated in the presence of oxygen 3. The COO2 and H2O produced by the combustion are trapped separately 4. The mass of each product is determined. From the masses of CO2 and H2O collected, the percent composition and empirical formula are calculated

Correctly order the steps necessary to balance a chemical equation

1. Write an unbalanced equation 2. Balance the atoms of each element in turn, by adding coefficients before the chemical formulas of reactants and products-compounds first, elements last 3. Adjust the coefficients such that the smallest whole-number coefficients are used 4. Do a final check to make sure the equation is balanced

What is the empirical formula of a compound containing C, H, and O if combustion of a 0.500-g sample of the compound produces 0.955 g CO2 and 0.587 g of H2O? (Put a number in every blank, even if it is a 0 or 1.) C____H____O____

2 6 1

When the following chemical equation is balanced correctly, what is the correct coefficient for each species? (Enter ALL numbers, including the digit 1, if required.) SO2(g) + O2 (g) → SO3 (g)

2 SO2 1 O2 2 SO3

When hydrogen gas is passed over powdered iron(III) oxide, iron metal and water vapor are formed. Select the correct balanced equation for this process

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

interpretations of the balanced equation 4C (s) + S8 (s) → 4CS2 (l)

4 moles of carbon react with 1 mole of S8 to form 4 moles of CS2. Carbon and S8 are reactants and CS2 is the product. 4 atoms of carbon react with 1 molecule of S8 to form 4 molecules of CS2

Match each reaction type with its distinguishing feature

Combination = Two or more reactants combine to form a single product. Decomposition = A single reactant forms two or more products. Combustion = A reactant rapidly reacts with O2(g) to form oxides, such as CO2(g).

What type of reaction is described by the equation shown below? CS2 (l) + 3O2 (g) → CO2 (g) + 2SO2 (g)

Combustion (Reason: In this reaction CS2 is being burned in oxygen. The reaction is therefore a combustion reaction.)

Match each of the following reactions with its general type

Decomposition = CuCO3 (s) → CuO (s) + CO2 (g) Combination = PF3 (g) + F2 (g) → PF5 (g) Combustion = C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O (l)

Which statement does NOT correctly describe a step in determining the empirical formula of a compound from combustion analysis data?

Determine the mass of a third element, if present, from the mass of its oxide produced in the combustion. (Reason: The mass of a third element is found by subtracting the masses of carbon and hydrogen from the total mass of the original sample.)

A student has done experiments to determine the empirical formula and the approximate molar mass of a substance. Which of the following methods should be used to determine the molecular formula?

Divide the approximate molar mass by the empirical formula mass

Which of the substances below are represented with their proper formulas? Elemental phosphorus, P4 Elemental oxygen, O2 Elemental copper, Cu Elemental sodium, Na+ Elemental boron, B2

Elemental phosphorus, P4 Elemental oxygen, O2 Elemental copper, Cu

What information can be obtained from a combustion analysis

Empirical formula of an organic compound (Reason: Combustion analysis gives the percent composition of each element, which allows us to determine the empirical formula) Percent composition of an organic compound

True or false: In order to balance the reaction of hydrogen gas (H2) with oxygen gas (O2) to form liquid H2O, a student adds a subscript of 2 to H2O (forming H2O2). This is an acceptable method of balancing the reaction described

False (Reason: Formulas of species involved in chemical reactions should never be changed, because this changes the identity of the compound. Only coefficients should be added to balance chemical equations.)

Which equation is a correct representation of the reaction shown? In the illustration, carbon is black, oxygen is red, and hydrogen is white

H2CO3 → CO2 + H2O

actions are permitted in balancing a chemical equation

Inserting coefficients before the formulas of reactants and products Multiplying all coefficients by a common factor

Of the elements listed, select all that typically occur as diatomic molecules. Sulfur, Carbon, Iodine, Helium, Nitrogen

Iodine (Reason: Iodine occurs as the diatomic molecule I 2 Nitrogen (Reason: Nitrogen occurs as the diatomic molecule N2)

"Aqueous solutions of calcium hydroxide and sodium phosphate react to form aqueous sodium hydroxide and solid calcium phosphate." In the reaction represented by the statement above, what are the reactants?

Na3PO4 Ca(OH)2

In a balanced chemical equation, which of the following must be the same on both sides of the equation

Number of atoms of each element

describe the symbols used to write a balanced equation

The symbol (g) indicates a substance in the gas phase. The symbol (s) is used for a powdered substance [Reason: A powder is a solid, and the symbol (s) would be used]

interpret the balanced chemical equation 4HCl (aq) + MnO2 (s) → MnCl2 (aq) + 2H2O (l) + Cl2 (g)?

Water is both a solvent and a product in this reaction. HCl is a reactant in this equation. The MnCl2 produced is dissolved in water.

In a(n) ____ reaction, a single product is formed from two or more reactants. The opposite of this reaction type is a(n) ____ reaction, in which a single reactant produces two or more products

combination decomposition

N2O4 → 2NO2 In the reaction represented by the chemical equation above, NO2 is the formula of the ______ and N2O4 is the formula of the ______

product, reactant

Match each symbol used in writing a chemical equation with its correct meaning.

→ indicates the conversion of reactants to products (s) indicates a substance in the solid state (aq) indicates a substance dissolved in H2O Δ indicates that the reaction is heated (l) indicates a substance in the liquid state