General Questions and Answers

All of the following are true of an oxidation-reduction reaction except: a. The sum of the charges for the products must be greater than the sum of the charges for the reactants b. A metal's redox activity can be predicted by its location on the periodic table c. It is impossible to reduce a metal without oxidizing a metal d. The oxidation number of the reducing agent increases

Does a reaction occur when aqueous solutions of ammonium sulfide and potassium nitrate are combined? yes no If a reaction does occur, write the net ionic equation. Use the solubility rules provided in the OWL Preparation Page to determine the solubility of compounds. Be sure to specify states such as (aq) or (s). If a box is not needed leave it blank.

Experiment #3: When the filtered milk was added to baking soda it... formed a liquid substance that would solidify if touched. it formed a liquid that would adhesive. underwent a chemical change. underwent a physical change.

Does a reaction occur when aqueous solutions of manganese(II) chloride and potassium nitrate are combined? yes no If a reaction does occur, write the net ionic equation. Use the solubility rules provided in the OWL Preparation Page to determine the solubility of compounds. Be sure to specify states such as (aq) or (s). If a box is not needed leave it blank. →

A watt is a unit of energy per unit time, and one watt (W) is equal to one joule per second (J-s-¹). An 80.0 W incandescent lightbulb produces about 7.00% of its energy as visible light. Assuming that the light has an average wavelength of 510.0 nm, calculate how many such photons are emitted per second by an 80.0 W incandescent lightbulb. number of photons per second:

You are presented with a white solid and told that due to careless labeling it is not clear if the substance is barium chloride, lead chloride, or zinc chloride. When you transfer the solid to a beaker and add water, the solid dissolves to give a clear solution. Next a Na₂SO₂(aq) solution is added and a white precipitate forms. What is the identity of the unknown white solid?

The compound ammonium sulfite is a strong electrolyte. Write the reaction when solid ammonium sulfite is put into water. Include states of matter in your answer.

How many kilojoules are released when 299 g of O2 is produced? Express your answer with the appropriate units.

Does a reaction occur when aqueous solutions of lead(II) nitrate and cobalt(II) sulfate are combined? If a reaction does occur, write the net ionic equation. Use the solubility rules provided in the OWL Preparation Page to determine the solubility of compounds. Be sure to specify states such as (aq) or (s). If a box is not needed leave it blank.

Liquid nitrogen trichloride is heated in a 2.50-L closed reaction vessel until it decomposes completely to gaseous elements. The resulting mixture exerts a pressure of 805 mmHg at 33°C. What is the partial pressure of each gas in the container? Pressure of N₂: torr Pressure of Cl₂: torr

A chemistry graduate student is given 250. mL of a 1.40 M methylamine (CH, NH₂) solution. Methylamine is a weak base with K =4.4 x 104. What mass of CH3NH₂Br should the student dissolve in the CH3NH₂ solution to turn it into a buffer with pH = 10.38 ? You may assume that the volume of the solution doesn't change when the CH3NH, Br is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits.

Suppose a 0.049 M aqueous solution of phosphoric acid (H, PO4) is prepared. Calculate the equilibrium molarity of HPO You'll find information on the properties of phosphoric acid in the ALEKS Data resource. Round your answer to 2 significant digits.

Consider the following definitions. 1 doz = 12 1 gross = 144 1 ream = 500 1 mol = 6.022 × 1023 Suppose you have 861 sheets of paper. How many dozens of paper do you have? How many gross of paper do you have?

A chemist dissolves 858. mg of pure perchloric acid in enough water to make up 250. mL of solution. Calculate the pH of the solution. Round your answer to 3 significant decimal places.

Part C In Part A, you found the number of moles of product (3.80 mol P2O5 ) formed from the given amount of phosphorus and excess oxygen. In Part B, you found the number of moles of product (3.40 mol P2O5 ) formed from the given amount of oxygen and excess phosphorus. Now, determine the number of moles of P2O5 is produced from the given amounts of phosphorus and oxygen. Express your answer to three significant figures and include the appropriate units.

How many atoms are in each elemental sample? 5.0 mol Cu Express your answer using two significant figures. N =

Learning Goal: To calculate theoretical and percent yields, given the masses of multiple reactants. A balanced chemical reaction gives the mole ratios between reactants and products. For example, one mole of white phosphorus, P4, reacts with five moles of oxygen, O2, to produce two moles of diphosphorus pentoxide, P2O5: P4+502 2P2O5 In this example, if we know the number of moles of phosphorus, we know that twice that much product can be made, assuming we have enough oxygen. Similarly, if we know the number of moles of oxygen, we know that two-fifths that much product can be made, assuming we have enough phosphorus. In a situation where you are given the mole amounts of both reactants, you should do this type of calculation individually for each one, finding two different values for the amount of product. The smaller of these two values is the maximum amount of product that can be made, also known as the theoretical yield. If you are given the masses of the reactants, you will first have to convert to moles. Once you have mole amounts, you can follow the procedure described above, applying the ratios shown in the balanced chemical equation. ✓ Correct This value is called the theoretical yield. It represents the maximum mass that could be produced if the reaction goes to completion. Percent yield If you were to perform this reaction in a lab, you would make far less than the theoretical yield of product due to a wide range of outside factors. We can compare the actual yield to the theoretical yield to calculate the percent yield: ▼ Part D percent yield = Keep in mind that the percent yield can be calculated using any unit of mass or moles, so long as they are the same. For example, you can divide moles by moles, or grams by grams, but you cannot divide moles by grams or vice versa. 0 What is the percent yield if the actual yield from this reaction is 299 g ? Express your answer to three significant figures and include the appropriate units. ► View Available Hint(s) μA Value Cubmit Review I Constants I Periodic Table actual yield theoretical yield Units x 100% ?

How many atoms are in each elemental sample? 27.4 mol Hg Express your answer using three significant figures. N=

Part B How many grams of CO are produced when 38.0 g of C reacts? Express your answer with the appropriate units. Part C How many grams of Fe can be produced when 7.95 g of Fe2O3 reacts? Express your answer with the appropriate units.

4Cr(s) + 302(g) → 2Cr2O3(s) Given 11.0 g of O2, how many grams of the product Cr2O3 could be produced? Express your answer with one decimal place and with appropriate units.

Azodicarbonamide, NH₂CON=NCONH2, is a blowing (foaming) agent for sponge rubber and expanded plastics. Its decomposition at 195-202°C is given by NH₂CON=NCONH₂(s) → NH3(g) + CO(g) + N₂(g) + HCNO(g) NH3(g) + HCNO(g)→ nonvolatile polymers(s) Assume that the reaction happens at STP, instead of at 195-202°C. Calculate the total volume of gases in the final mixture that results from the decomposition of 1.83 g of azodicarbonamide. mL

Iron and oxygen react to form iron (III) oxide. 4Fe(s) + 302(g) → 2Fe2O3(s) Determine the limiting reactant in each of the following mixtures of reactants: Part A 2.0 mol of Fe and 6.0 mol of 02 6.0 mol of O₂ 2.0 mol of Fe

How many moles of PC15 can be produced from 29.0 g of P4 (and excess Cl₂)?

What is the percent yield of iron if the reaction of 64.5 g of iron (III) oxide produces 16.0 g of iron? priato unite

Write balanced molecular and net ionic equations for the following reactions, and identify the gas formed in each: (a) solid cadmium sulfide reacts with an aqueous solution of sulfuric acid; (b) solid magnesium carbonate reacts with an aqueous solution of perchloric acid.

A chemist dissolves 353. mg of pure potassium hydroxide in enough water to make up 80. mL of solution. Calculate the pH of the solution. (The temperature of the solution is 25 °C.)

Which of the following requires a chemical change? A. Letting the fizz escape from a soda B. Melting chocolate on a graham cracker C. Toasting a marshmallow over a fire OD. Blending mustard and ketchup on a bun

Which of the following is a decomposition reaction? O Pb(C2H302)2(aq) + 2 NaCl(aq) → PbCl2(s) + 2 NaC2H3O2(aq) O Zn(s) + 2 AgNO3(aq) → 2 Ag(s) + Zn(NO3)2(aq) O 2 Na(s) + Cl₂(aq) → 2NaCl(s) O 202 + CH4 → CO₂ + 2 H₂O O CaCO3(s)→ CaO(s) + CO2 (g) O HCl(aq) + LiOH(aq) → LiCl(aq) + H₂O(l)

The acid dissociation constant K of trimethylacetic acid (HC (CH₂), CO₂) is 9.33 × 100. Calculate the pH of a 0.47 M solution of trimethylacetic acid. Round your answer to 1 decimal place.

4.36 An aqueous solution of an unknown solute is tested with litmus paper and found to be acidic. The solution is weakly conducting compared with a solution of NaCl of the same concentration. Which of the following substances could the unknown be: KOH, NH₂, HNO₂, KCIO₂, H₂PO3, CH,COCH, (acetone)? Explain.

Predict the products of the following reaction: (Hint: the charge of the metal does not change) Li₂S+ Cr(NO3)4 → O LiCr + SNO3 Li₂(NO3)4 + CrS O Li₂Cr + S(NO3)4 O LINO3 + CrS₂ O Cr₂S3 + LINO O Cr4S + Li(NO3)2 O CrS + LINO3

According to the following reaction, what amount of A12S3 remains when 20.00 g of A12S3 and 2.00 g of H20 are reacted? A few of the molar masses are as follows: A12S3 = 150.17 g/mol, H2O = 18.02 g/mol. A12S3(s) + 6 H2O(1) →2 Al(OH)3(s) + 3 H2S(g) 28.33 g 14.00 g 8.33 g 19.78 g O 17.22 g

4.53 Write balanced molecular and net ionic equations for the reactions of (a) manganese with dilute sulfuric acid (b) chromium with hydrobromic acid (c) tin with hydrochloric acid (d) aluminum with formic acid, HCOOH.

4.44 As K₂O dissolves in water, the oxide ion reacts with water molecules to form hydroxide ions. (a) Write the molecular and net ionic equations for this reaction. (b) Based on the definitions of acid and base, what ion is the base in this reaction? (c) What is the acid in the reaction? (d) What is the spectator ion in the reaction?

What pressure in atm is equivalent to 105.2 kPa?

Predict the products and balance the equations. All reactants, products, states, and coefficients should be shown. The first blank is the coefficient (1, 2, 3.....). The second blank is the chemical formula (assume all numbers should be subscripted, AgNO3 would be written AgNO3). In parentheses is the state of matter (use s, I, g, or aq only). Note that on the reactant's side of the equation, the only blank is for the coefficient since the formula and state of matter are given. AgNO3(aq)+ 1. 2. (s) + C5H₂O(g) + (g) + 3. All coefficients are one. MgO (s) +H₂O (1)→ Na₂CrO4(aq) → (aq) O₂(g) → (1) (s)

For the following reaction, 56.5 grams of potassium hydroxide are allowed to react with 30.2 grams of phosphoric acid. potassium hydroxide (aq) + phosphoric acid (aq) potassium phosphate (aq) + water (1) What is the maximum amount of potassium phosphate that can be formed? What is the FORMULA for the limiting reagent? What amount of the excess reagent remains after the reaction is complete? grams grams

For the following reaction, 53.3 grams of iron(III) oxide are allowed to react with 22.3 grams of aluminum. iron(III) oxide (s) + aluminum (s)-aluminum oxide (s) + iron (s) What is the maximum amount of aluminum oxide that can be formed? What is the FORMULA for the limiting reagent? What amount of the excess reagent remains after the reaction is complete? grams grams

(4.4) Which reactant is in excess and what quantity (in moles) are in excess after the acid-base neutralization reaction of 250 mL of 0.127 M sulfuric acid with 0.200 L of 0.254 M NaOH? H₂SO4(aq) + 2 NaOH - Na2SO4(aq) + 2 H₂O(1)

The function of sodium thiosulfate in photographic developing is to remove excess silver bromide by the reaction 2 Na2S2O3 + AgBr Na3Ag(S203)2 + NaBr. What is the percent yield if the reaction of 8.18 g of sodium thiosulfate produces 2.61 g of sodium bromide?

How many grams of copper (III) nitrate are contained in a 25 mL solution if the nitrate ion concentration is 0.739 M. Please note that the given concentration is for the nitrate ion. (A) 11.1 g (B) 4.61 g (C) 13.8 g (D) 1. 54 g (E) 0.739 g

Calculate the number of moles of 0.760 g of CaCO3 Determine the number of grams in 1.30 moles of PbCl2 3.97 x 1024 molecules of NO has what mass? Calculate the percent composition of each element in Na3PC

Complete and balance the chemical equation for the reaction of aluminum with hydrochloric acid on a separate piece of paper. Then, enter the information into the blanks provided. First blank is the coefficient (1,2,3,...). Second blank is the formula. Third blank in parentheses is the state of matter (s, I, g, aq). Assume all numbers should be subscripted, AgNO3 would be written AgNO3 in the blank. Give answers in the following order: aluminum + hydrochloric acid → product with aluminum + other product

A sample of MgCl₂(s) is added to water and the number of chloride ions is measured to be 8 x 10²²2. Derive an equation for the MgCl, concentration by dragging the components into the empty boxes. Include the units in your equation. The total volume of the solution is 5.0 L.

Explain the role that protons play in acid-base neutralization reactions. Construct a molecular representation for the reaction between hydrochloric acid and sodium chloride (reactants and products).

How many moles of NH3 are produced when 1.5 mol of H₂ reacts? Express the number of moles to two significant figures. ___mol NH3

If 1 Calorie (nutritional "Calorie") = 4.18 kJ, how many kJ of energy can be released by an apple containing 125 Cal? A) 0.0334 kJ B) 29.9 kJ C) 522 kJ D) 5.22 x 10^5 kJ

Determine the concentrations of BaBr2, Ba2+, and Br in a solution prepared by dissolving 2.20 x 10-4 g BaBr₂ in 1.75 L of water. Express all three concentrations in molarity. Additionally, express the concentrations of the ionic species in parts per million (ppm). [BaBr₂] = [Ba²+] = [Br] = M M M [Ba²+] = [Br] = ppm ppm

A compound is 53.31% C, 11.18% H, and 35.51% O by mass. What is its empirical formula? Insert subscripts as needed. empirical formula: CHO The molecular mass of the compound is 90 amu. What is the molecular formula? Insert subscripts as needed. molecular formula: CHO

You may use a printed copy of the periodic table, your stoichiometry general formulas sheet, and a calculator to solve this problem. a. If 30.0 g nitrogen gas react with 30.0 g of hydrogen gas according to the equation below, what will be the expected (theoretical) yield of ammonia? N₂ (g) + 3 H₂ (g) → 2 NH3 (g) b. What is the limiting reactant? c. If 30.0 g of ammonia actually get produced, what is the percent yield of ammonia for this reaction?