CHE 131 Lecture Notes - Lecture 10: Strontium Hydroxide, Barium Hydroxide, Sodium Hydroxide

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aquamarinehound156

22 Feb 2017

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Stony Brook University

Department

Chemistry

Course

CHE 131

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lacy

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CHE 131 Full Course Notes

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Solutions can involve all physical states (gas, solid, liquid) Real world: most solutions in medicine and agriculture occur in aqueous solutions. A solution in a homogenous mixture of two or more substances. Solvent substance present in the greatest quantity. Solutes substances dissolved in the solvent. Concentration (amount of solute)/ (amount of solution) Ppm (parts per million) = (grams of solute)/ (10^6 grams of solution) Molarity moles of solute per liter of solution. M = ((grams of solute)/ (molar mass of solute))/ liter of solution. Stock solution: concentrated solution (aka has a high solute-to-solvent ratio) Dilution: preparation of dilute solution (aka low solute-to-solvent ratio) by adding solvent to a given volume of stock solution. Lecture 11 & 12: electrolytes; acid-base reactions; precipitation. Soluble cations: group 1 ions (alkali metals) and nh4. Soluble anions: no3 and ch3coo (acetate, halides (group 17) Exceptions: ag, cu, pb, hg2: sulfates (so4) Combining anions/cations not listed above will result in formation of an insoluble compound.

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Experiment 10 Colligative Properties Introduction A pinch of wa make boiling water hotter. A handful will clear the snow from your steps. Every day we the physical properties of materials around us, but often don't know why we use these particular s or what chemistry is involved. Modifying the temperature of phase changes, by adding a second chemical to the pure solvent are examples of manipulating the Colligative Properties of a solution. this lab, we will study how varying the concentration and type of a salt affects the point of a solution. Colligative properties are properties of a solution containing 2 or more components. Typically, the primary is the solvent and the other called the such as color or hardness, properties depend on the number of particles of astute in the not the identity of the In many cases, the rokute will determine the number of solute particles (degree of ionization, solubility, etc,) in the solvent, but a colligative property does not depend upon the nature of the particles. Two colligative properties commonly encountered are boiling point elevation and freezing point depression (the temperature of of a is lower than of pure solvent). We will be studying boiling point elevation in this Most of the previous work that you have done with solutions has involved units of molarity, M, or moles of solute per liter of solution. Boiling point elevation calculations (as well as those for freezing point depression) or moles of solute per kilogram of solvent. boili change of temperature. When the temperature of a solution changes, the volume of the solution also changes. Since molarity depends on a change in wil the solution's molarity. Molality depends on the mass of the solvent. and thus is independent of temperature. n't Hoff Factor salt into and the of moles inorganic salts in an aque the based on the addition of the number dissociates, the total number of particles in the solution will be of cations and anions produced from the dissociation. Thus; Nacion Na Choaa (2moles of particles) Cacbrs Ca +2ch (3moles of particles) The quantity of particles produced per mole of solute is called the van'tHoff factor and is given the symbol, i, If 1 mole of sodium chloride were completely dissociated, iwould be 2. This theory works very well for dilute solutions and non-electrolytes (i 1, no dissociation at all since nonelectrolytes not ionize), For does not always apply to more concentrated solutions. Thus, when there are a large number of particles in a solution, they have a tendency to recombine as the salt and you don't get 100% dissociation. example, at a NaCl concentration of 0.1M, iwill be 1.81 (90% dissociation) rather than 2 (100%). Boiling Point Elevation solute causes the solution to boil at a higher When a solution is heated, the presence of a non-volatile point of the pure liquid and the temperature than the pure The difference between the boiling boiling point of the solution is: 169

1. Consider the unbalanced equation for the reaction of solid lead with a silver nitrate solution.

_____Pb (s) + ______AgNO3 (ac) â ______Pb(NO3)2 (ac) + _______Ag (s)

a. Balance the equation.

b. How many moles of silver nitrate are required to react completely with 9.3 mol of lead?

c. How many moles of silver, Ag, are formed by the complete reaction of 28.4 mol of Pb?

2. For the following reaction: _____CaO (s) + _____CO2 (g) â _____CaCO3 (s), Calculate how many grams of CaCO3, are formed when 2.4 g of CaO Do they react completely with CO2?

3. For the following reaction: 2 Li (s) + F2 (g) â 2 LiF (s), find the reagent limiting with the amounts of 1.0 mol of Li and 1.0 mol of F2.

4. For the next reaction, determine the limiting reagent, calculate the yield Theoretical product in grams with 5.5 g of Al and 19.8 g of Cl2.

2 Al (s) + 3 Cl2 (g) â 2 AlCl3 (s)

5. Consider the reaction between NiS2 and O2:

2 NiS2 (s) + 5 O2 (g) â 2 NiO (s) + 4 SO2 (g)

When 11.2 g of NiS2 react with 5.43 g of O2, 4.86 g of NiO are obtained. Determine the limiting reagent, the theoretical yield of NiO and the% yield for the reaction.

6. How many atoms of mercury are in 5.8 mol of mercury?

7. Complete the following table:

Element Moles Mass Number of molecules

8. How many grams of sodium are there in 1.00 g of each of the following compounds?

a. Na3PO4

b. NaC7H5O2

c. Na2C6H6O7

9. A sample of 4.78 g of aluminum reacts completely with oxygen to form 6.67 g of aluminum oxide. Use the data to calculate the percent of composition by mass.

10. Citric acid, the compound responsible for the bitter taste in lemons, has the following composition: C - 37.51%

H - 4.40%

O - 58.29%

Calculate the empirical formula.

11. A compound containing phosphorus and oxygen has a molar mass of 219.9 g / mol and an empirical formula of P2O3. Find the molecular formula of compound.

12. It is a term used in chemistry, to describe a system in which a

or more substances, are mixed or dissolved homogeneously in another

substance.

a. Mixture

b. Solution

c. Compound

d. None of the above

13. It is the component that is in a solution, in smaller quantity.

a. Solution

b. Solvent

c. Solvent

d. Soluto

14. It is the component that is in a solution in greater quantity.

a. Solution

b. Solvent

c. Solvent

d. The answers b and c are correct.

15. The quantitative expression of the dissolved amount of solute in a quantity determined solvent is known as:

a. Solution

b. Volume

c. Concentration

d. Stoichiometry

16.Express the moles of solute among the liters of solution

a. Molality

b. Molarity

c. % weight by volume

d. % weight by weight

17.Express the moles of solute between kg of solvent

a. Molarity

b. ppm

c. ppt

d. Molality

18. What is the molarity of a solution prepared by dissolving 7.50 g of nitrate of magnesium, Mg (NO3) 2 in enough water to prepare 25.0 mL of solution?

a. 10.3 M

b. 5.6 M

c. 6.5 M

d. 2.03 M

19. How many grams of sodium chloride, NaCl are needed to prepare 125 mL of 0.037 M NaCl solution

a. 1.021 M

b. 0.268 M

c. 0.201 M

d. 0.500 M

20. Calculate the molality of a solution containing 12.5 g of ethylene glycol (C2H6O2) dissolved in 135 g of water.

21. A solution of ethylene glycol contains 21.2 g of ethylene glycol (C2H6O2) in 85.4 mL of water. Calculate the freezing point and the boiling point of the solution. (Assume the water density is 1.00 g / mL)

22. At what volume should you dilute 75 mL of a 10.0 M solution of H2SO4 to obtain a 1.75 M solution of H2SO4.

This is for the lab practical I take on Tuesday night. If you could answer each one and show your work/ explain that'd be amazing so I can do well on the actual practical on Tuesday! Thank you!

Chemistry 211 Lab Final Study Guide Spring 2015

Useful Information:
1 ampere =coulomb/sec
Faradayâs constant = 96,500 coulombs/mole of electrons
Molar mass of Au = 197.0 g/mole, Molar mass of Cu = 63.55 g/mole
m = moles , ' â

c kg

ÎTf

= Tf

â Tf

where Tf is for the pure solvent and Tf

is for the mixture.

ÎT = (K

)(m ) ,

m = (

(mass of

solute, g )
)( ).

f f c

c molar

mass, g

mol â1

mass of

solvent, kg

7. Next question

(a) If you weigh 6.355 grams of copper, add concentrated nitric acid to dissolve it, and then dilute the solution to a total volume of 50 mL, how many moles of copper are in this solution?

(b) For the equilibrium reaction 3H2(g) + N2(g) â 2NH3(g), what is the equilibrium constant expression, Kc, for this reaction? (5pts)

8. Suppose at some temperature, the equilibrium concentration of H2 is 0.45M, the equilibrium concentration of N2 is 0.38M, and the equilibrium concentration of NH3 is 0.42M. What is the value of the equilibrium constant for the reaction 3H2(g) + N2(g) â 2NH3(g) at this temperature? (Show your work. No credit will be given if your work is not shown.)

9. Next question
(a) If you need 0.0534 moles of NaOH to reach equivalent point in the titration with acetic acid, how many mL of 0.09876M NaOH will you need?

(b) The Ksp of Cu(OH)2 is 2.2x10-20, what is the solubility of Cu(OH)2?

10. Next question
(a) In non-sulfide qualitative analysis of representative cations, the Group A cations comprising of Pb2+,

Hg2+, and Ag+ give a precipitate with solution.
(b) From a solution containing mixture of Pb2+, Fe3+, and Al3+, Pb2+ is removed by adding HCl solution. To the remaining cation mixture, on making the solution basic with NH3 (pH=9 â 10), both the cations form precipitate. Further analysis of the cation mixture containing Fe3+ and Al3+ is carried out by adding NaOH solution.

Aluminum hydroxide (dissolves/remains undissolved) in NaOH solution while Ferric hydroxide ( dissolves/remains undissolved).
(c) Fe(OH)3 precipitate is dissolved in minimal amount of aqueous HCl which gives a

yellow solution. To this solution addition of solution (at pH = 4 â 5) yields a dark blue solid known as Prussian Blue.

(d) Describe the method for checking for completeness of precipitate in qualitative analysis of ions.

CHE 131 Lecture Notes - Lecture 10: Strontium Hydroxide, Barium Hydroxide, Sodium Hydroxide

CHE 131 Full Course Notes

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