Qualitative analysis Questions and Answers

Solid phosphorus (P)and chlorine (Cl₂) gas react to form solid phosphorus pentachloride (PCI5). Suppose you have 9.0 mol of P and 3.0 mol of Cl, in a reactor.

Potassium hydrogen phthalate a solid, monoprotic acid frequently used in the laboratory to standardize strong base solutions. It has the unwieldy formula of KHC8H4O4. This is often written in shorthand notation as KHP. How many grams of KHP are needed to exactly neutralize 20.7 mL of a 0.270 M sodium hydroxide solution ?

59. Consider the thermochemical equation for the combustion of acetone (C3H6O), the main ingredient in nail polish remover. C3H6O(1) + 4 O2(g) -> 3 CO₂(g) + 3 H₂O(g) ΔH rxn = -1790 kJ If a bottle of nail polish remover contains 177 mL of acetone, how much heat is released by its complete combustion? The density of acetone is 0.788 g/mL.

"Smelling salts," which are used to revive someone who has fainted, typically contain ammonium carbonate, (NH4)2CO3. Ammonium carbonate decomposes readily to form ammonia, carbon dioxide, and water. The strong odor of the ammonia usually restores consciousness in the person who has fainted. The unbalanced equation is (NH4)2CO3 (s)→ NH3(g) + CO₂(g) + H₂O(g) Calculate the mass of ammonia gas that is produced if 2.55 g of ammonium carbonate decomposes completely.

For the following reaction, 35.1 grams of aluminum oxide are allowed to react with 90.6 grams of sulfuric acid. aluminum oxide(s) + sulfuric acid(aq) → aluminum sulfate(aq) + water(l) What is the maximum amount of aluminum sulfate that can be formed? What is the FORMULA for the limiting reagent? What amount of the excess reagent remains after the reaction is complete?

The compound cobalt(II) acetate is a strong electrolyte. Write the reaction when solid cobalt(II) acetate is put into water. Include states of matter in your answer.

The compound sodium thiosulfate pentahydrate, Na2S2O3-5H₂O, is important commercially to the photography business as "hypo", because it has the ability to dissolve unreacted silver salts from photographic film during development. Sodium thiosulfate pentahydrate can be produced by boiling elemental sulfur in an aqueous solution of sodium sulfite. S8 (s) + Na₂SO3(aq) + H₂O(l) → Na2S2O3.5H₂O(s) (unbalanced) What is the theoretical yield of sodium thiosulfate pentahydrate when 2.90 g of sulfur is boiled with 14.4 g of sodium sulfite? Theoretical yield = Sodium thiosulfate pentahydrate is very soluble in water. What is the percent yield of the synthesis if a student doing this experiment is able to isolate (collect) only 5.20 g of the product? Percent yield =

What is the enthalpy for reaction 1 reversed? reaction 1 reversed: 2NO+ O2---> 2NO2

It takes 54.0 J to raise the temperature of an 9.90 g piece of unknown metal from 13.0°C to 24.9 °C. What is the specific heat for the metal? Express your answer with the appropriate units.

The amount of boiling water required to raise the temperature of 25.0 kg of water in the bath to body temperature is 4.80 kg. In this process, the heat lost by the boiling water is equal to the heat gained by the room-temperature water. How much heat was transferred in this process? Express your answer to four significant figures and include the appropriate units.

Propane (C3H8) burns according to the following balanced equation: C3H8(g) +5O2(g) →3CO₂(g) + 4H₂O(g) Calculate ΔH for this reaction using standard enthalpies of formation. (The standard enthalpy of formation of gaseous propane is -103.9 kJ/mol.) Express the enthalpy in kilojoules to four significant figures.

A total of 2.00 mol of a compound is allowed to react with water in a foam coffee cup and the reaction produces 189 g of solution. The reaction caused the temperature of the solution to rise from 21.00 to 24.70 °C. What is the enthalpy of this reaction? Assume that no heat is lost to the surroundings or to the coffee cup itself and that the specific heat of the solution is the same as that of pure water. Enter your answer in kilojoules per mole of compound to three significant figures.

When a 3.25 g sample of solid sodium hydroxide was dissolved in a calorimeter in 100.0 g of water, the temperature rose from 23.9 C to 32.0 C. Calculate ΔH in kJ/mol NaOH) for the solution process: NaOH(s) --> Na+ (aq) + OH-(aq) Assume it's a perfect calorimeter and that the specific heat of the solution is the same as that of pure water.

The amount of space an object occupies may be found by h. mass f. length g. time i. volume Which of the following measurements is most precise? a. 5.432 C. 5.4 d. 5 b. 5.43

You have three known solutions: 1) Na₂CO3 2) BaCl2 3) KNO3 Even though you know that you have these three solutions, you do not know which one is which because they are not labeled. Which one of the following reagents should you add to each solution to be able to accurately identify and label them? Select one: A. We need more than one of these reagents to be able to identify all three solutions. B. CaCl2 C. H₂SO4 D. HCI E. NaOH

A 14.9 g sample of an aqueous solution of hydrochloric acid contains an unknown amount of the acid. If 16.0 mL of 1.03 M sodium hydroxide are required to neutralize the hydrochloric acid, what is the percent by mass of hydrochloric acid in the mixture? % by mass

A 1.45-g sample of phosphorus burns in air and forms 2.57 g of a phosphorus oxide. Calculate the empirical for- mula of the oxide. (Hint: Determine the mass of oxygen in the 2.57 g of phosphorus oxide by determining the differ- ence in mass before and after the phosphorus burns in air.)

A chemistry student weighs out 0.215 g of phosphoric acid (H₂PO4), a triprotic acid, into a 250. mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1500 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the final equivalence point. Round your answer to 3 significant digits.

What mass of iron(III) hydroxide precipitate can be produced by reacting 85.0 mL of 0.290 M iron(III) nitrate with 199 mL of 0.200 M sodium hydroxide? Mass =

A chemistry student weighs out 0.163 g of acrylic acid (HCH₂CHCO₂) into a 250. mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1700 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the equivalence point. Round your answer to 3 significant digits.

A chemistry student weighs out 0.158 g of ascorbic acid (H₂C6H6O6), a diprotic acid, into a 250. mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1000 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the final equivalence point. Round your answer to 3 significant digits.

Show the correct link to the experimental conditions on the right: Supersaturated Dialysis Diffusion Osmosis • Copper ions can pass through a semi-permeable membrane while starch colloidal particles are held back • When a few crystals of potassium permanganate were added to an undisturbed water sample, it shows a purple coloration slowly expanding through water. • Water molecules pass through a semi-permeable tissue membrane from a 0.89% salt solution to a 10% salt solution Solution in which addition of sodium chloride crystallizes

Calculate the solubility of oxygen in water at 25° C when the partial pressure of oxygen is 0.22 atm. The Henry's law constant for oxygen in water is 1.3 x10 mol/L.atm 8pts 218 g of glucose (molar mass 180.2g/mol) is dissolved in 460 ml. of water at 30° C. The density of water is 1.00g/ml. The Vapor pressure of pure water is 31.82 mm Hg. What isthe vapor pressure of the solution? How much is the vapor pressure lowering? 20 pts

Calculate the volume of 0.660-M NaOH solution needed to completely neutralize 16.3 mL of a 0.360-M solution of the monoprotic acid HBr.

Sort the following molecules according to increasing bond angles about the central atom: SF6, IF 5, NF3, CIF₂- IF5, SF 6, NF3, CIF₂- SF6, CIF2-, NF3, IFS SF6, NF3, IFS, CIF₂- IF5, NF3, CIF2-, SF6 CIF₂-, NF3, SF6, IF5

A sample of iron reacted with hydrochloric acid. The liberated hydrogen occupied 40.1 mL when collected over water at 27°C at a barometric pressure of 750 torr. What is the mass of the sample of iron? (Because of the collection of gas over water, the vapor pressure of the water must be subtracted from the barometric pressure to find the pressure of the hydrogen gas.) If you wanted to prepare 50.0 mL of hydrogen, collected over water at 25°C on a day when the barometric pressure was 730 torr, what mass of aluminum would you react with a hydrochloric acid? (Balance the equation first.) Al (s) + HCI (aq) → AICI3(aq) + _H₂(g)

A 12.8 g sample of an aqueous solution of hydrochloric acid contains an unknown amount of the acid. If 20.4 mL of 0.634 M sodium hydroxide are required to neutralize the hydrochloric acid, what is the percent by mass of hydrochloric acid in the mixture?

Calculate the volume of 0.410-M NaOH solution needed to completely neutralize 64.8 mL of a 0.820-M solution of the monoprotic acid HCl.

The Lewis representation above depicts a reaction between a halogen (blue) and a main-group element from group electron(s) to complete its octet, and gains these electrons by forming In this representation, each Y atom needs atoms of X There are _ unshared electron pair(s) and The bonds in the product are bonding electron pair(s) in the product molecule. (red). bond(s) with

What is the net ionic equation for the reaction below? 3 CaCl₂ (aq) + 2 Na3PO4 (aq) -> Ca3(PO4)2 (s) +6 NaCl (aq) 3 Ca²+ (aq) + 2 PO4³- (aq) → Ca3(PO4)2 (s) PO4³- (aq) + Cl¯ (aq) → CIPO4- (aq) Ca²+ (aq) + Na+ (aq) → CaNa (aq) 6 Na+ (aq) + 6 Cl¯ (aq) → 6 NaCl (aq)

Ethylene Glycol (EG) is a common automobile antifreeze. The molar mass of EG is 15pts 62.01g/moles. 651 g of EG is dissolved in 2505 g of water. Calculate- a. The Freezing point of the solution. Kr= 1.86 °C/m FP water = 0° C b. The Boiling point of the solution. Km = 0.52° C/m BP water- 100 °C George makes spaghetti for dinner. He places 4.01 kg of water in a pan and brings it to a Boil. Before adding pasta, he adds 58 g of table salt (NaCl) to the water and again brings It to a boil. What is the boiling point of the salt solution? 12 pts

You are given 250 mL solution and need to adjust the drip rate for a patient. Before you begin you notice that the pump dispenses 15 drops per mL. Based on this information, how many drops will the pump dispense per sec if it runs for one hour? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. 1 drop/sec 1.35x10 drops/sec 60,000 drops/sec 0.0046 drops/sec

To make rust-resistant, a jewelry is electroplated by tin (Sn). Molar mass of Sn is 118.710 g/mol. The half-reaction related to this process is shown below: Sn2+ (aq) + 2e¯→ Sn(s) How much time in seconds would it take for 325 mg of Sn to be plated at a current of 4.7 A?

Given that zinc reacts with iodine in the fixed mass ratio of 1 gram of zinc to 3.88 grams of iodine, how many grams of iodine are required to completely react with 4.2 grams of zinc? The unit conversion you will use here is: grams of Zinc/ grams of iodine Fill in the blanks to set up the problem mathematically: 4.2 g of zinc x grams of grams number of grams of zinc required= Type your answer here

Calculate the pH of a 0.321 M solution of NaNO₂. The ionization constant, K₁, for the acid, HNO₂, is 4.60 × 10^-4.

Upon combustion, an unknown compound containing only carbon and hydrogen produces 39.86 g carbon dioxide and 8.16 g water. Determine the empirical formula of the unknown compound. C3H2 CH C₂H CH₂ C3H

Consider the reaction. 2 CO(g) + Oz(g) -> 2 CO2(g) ΔH = -566.0 kJ a) Is the reaction exothermic of endothermic? b) 2.80 g of CO let to react with excess of O2. How much heat will be released or absorbed by the system?

150. mL of 0.350 M HCI was mixed with 150. mL of 0.350 M NaOH in a calorimeter (of negligible heat capacity). The initial temperature of the HCI and NaOH solutions was the same, 23.25°C, and the final temperature of the mixed solution was 25.60°C. Calculate the heat of neutralization for the reaction: NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O) dsol = 1.00 g/mL; S.H.sol = 4.184 J/g °C

Calculate the mass of dinitrogen tetroxide (N₂O4) that contains a million (1.0 × 106) nitrogen atoms. Be sure your answer has a unit symbol if necessary, and round it to 2 significant digits.

Ammonia gas reacts with oxygen gas, O₂ (g), to produce nitrogen dioxide and water. When 32.4 g of ammonia gas reacts with 87.3 g of oxygen gas to produce 64.5 g of nitrogen dioxide, what is the percent yield for the reaction? For the hydrogen atom, H, you must use a molar mass of 1.008 g/mol in your calculations and for the nitrogen atom, N, use a molar mass of 14.01 g/mol in your calculations. Do NOT include units in your answer. Do not include "%" in your answer. If you round during your calculation, be sure to keep at least three (3) decimal places. Report your answer to one (1) decimal place.

A stock solution containing Mn²+ ions was prepared by dissolving 1.861 g pure manganese metal in nitric acid and diluting to a final volume of 1.000 L. The following solutions were then prepared by dilution: For solution 4, 40.00 mL of stock solution was diluted to 1000.0 mL. For solution B, 20.00 mL of solution A was diluted to 250.0 mL. For solution C, 10.00 mL of solution B was diluted to 550.0 mL. Calculate the concentration of the stock solution.

One serving (25 grams) of sour cream and onion potato chips contains 9 g of fat, 14 g of carbohydrates, and 2 g of protein. Estimate the number of calories. [Hint: One gram of protein or one gram of carbohydrate typically releases about 4 Cal/g, while fat releases 9 Cal/g.] Report your answer to 1 significant figure.

Iron concentrations greater than 6.30×10-6 M in water used for laundry purposes can cause staining. What [OH-] is required to reduce Fe2+ to this level by precipitation of Fe(OH)2? (Ksp = 8.0x10-16)

A chemist prepares a solution of magnesium fluoride (MgF₂) by measuring out 0.00399 μmol of magnesium fluoride into a 100. mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mmol/L of the chemist's magnesium fluoride solution. Round your answer to 3 significant digits.

A mixture of CaCO3 and CaO weighing 0.693 g was heated to produce gaseous CO₂. After heating, the remaining solid weighed 0.508 g. Assuming all the CaCO3 broke down to CaO and CO2, calculate the mass percent of CaCO3 in the original mixture.

Aluminum sulfate, known as cake alum, has a wide range of uses, from dyeing leather and cloth to purifying sewage. In aqueous solution, it reacts with base to form a white precipitate. (a) Write balanced total and net ionic equations for its reaction with aqueous NaOH. (b) What mass of precipitate forms when 185.5 mL of 0.533 M NaOH is added to 627 mL of a solution that contains 15.8 g of aluminum sulfate per liter?

In a titration of HNO3, you add a few drops of phenolphthalein indicator to 50.00 mL of acid in a flask. You quickly add 20.00 mL of 0.0502 M NaOH but overshoot the end point, and the solution turns deep pink. Instead of starting over, you add 30.00 mL of the acid, and the solution turns colorless. Then, it takes 3.22 mL of the NaOH to reach the end point. (a) What is the concentration of the HNO3 solution? (b) How many moles of NaOH were in excess after the first addition?

Do NOT include units in your answer. If you round during your calculation, be sure to keep at least three (3) decimal places. Report your answer to one (1) decimal place. Answer:

Magnesium metal, Mg (s), reacts with water, H₂O (l), to form magnesium hydroxide and hydrogen gas, H₂ (g). What mass of hydrogen gas can be produced in the reaction of 146.0 g of magnesium with 193.3 g of water? Assume the reaction goes to completion and that it occurs at room temperature and pressure. Molar mass: for the hydrogen atom, H, must use 1.008 g/mol. Thus, for H₂ (g) use 2.016 g/mol Do NOT include units in your answer. If you round during your calculation, be sure to keep at least three (3) decimal places. Report your answer to one (1) decimal place.

Ammonia gas reacts with oxygen gas, O₂(g), to produce nitrogen dioxide and water. When 28.5 g of ammonia gas reacts with 83.4 g of oxygen gas to produce 62.6 g of nitrogen dioxide, what is the percent yield of the reaction? Molar mass: for the hydrogen atom, H, must use 1.008 g/mol and for the nitrogen atom, N, use 14.01 g/mol Do NOT include units in your answer. If you round during your calculation, be sure to keep at least three (3) decimal places. Report your answer to one (1) decimal place.