A chemical analysis of a surface water yields the following data:

Ion      Concentration (mg/L)

Ca2+ 90

Mg2+ 30

Na+ 72

K+ 6

Cl- 120

SO42- 225

HCO3- 165

pH 7.5

What concentration of Cl- (mg/L) would make the cations and anions balance?  

how much 5.80 M NaOH must be added to 460.0 mL of a buffer that is 0.0200 M acetic acid and 0.0250 M sodium acetate to raise the pH to 5.75

Arrange in order of increasing atomic size. (Use the appropriate <, =, or > symbol to separate substances in the list.)

(a) the Period 2 elements C, Ne, and O

(b) the Group 4A elements Ge, C, and Pb

A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0 mL of a pH = 10.18 solution.

= _________ mL

In a 1.0× 10–2 M solution of CH3NH3Br(aq), identify the relative molar amounts of these species. List them from Most to Least, please.

H₂O

Br^-

CH₃NH₂

CH₃NH₃

OH^-

H₃O⁺

HBr

How many moles of KF should be added to 0.50 L of a 0.10 M HF solution to prepare a buffer with a pH of 2.84?

Consider the following reaction. 2 A + B −→ P A table of initial rates with initial concentrations of A and B is given below. [A]o (M) [B]o (M) rate M s 0.2 0.1 1.2 × 10−5 0.4 0.1 2.4 × 10−5 0.4 0.2 9.2 × 10−5 0.1 0.1 6.0 × 10−6 What is the rate expression? (a) r = k[A] [B]2 (b) r = k[A] [B] (c) r = k[A]2 [B] (d) r = k[A]2 [B]2

Part A) Approximately how many mL of 5% BaCl2 solution would be required to precipitate all the sulfate if we assume that your samples are pure Magnesium sulfate? Assume that the density of the barium chloride solution is 1.00 g/mL.

Part B) If the samples were pure potassium sulfate would you require a smaller or larger volume of barium chloride solution than the amount calculated in (Part A) above?

Mass of Sulfate,

Trial 1) 0.0914 grams

Trial 2) 0.0854 grams

Trial 3) 0.0859 grams

These were determined by stiochemetric calculations

0.2222g x (1 mole BaSO4 / 233.39 g) x (1 mole sulfate / 1 moe BaSO4) x (96.0576 g Sulfate / 1 mole sulfate) = 0.0914 grams SO₄^2-

0.2075g x (1 mole BaSO4 / 233.39 g) x (1 mole sulfate / 1 moe BaSO4) x (96.0576 g Sulfate / 1 mole sulfate) = 0.0854 grams SO₄^2-

0.2087g x (1 mole BaSO4 / 233.39 g) x (1 mole sulfate / 1 moe BaSO4) x (96.0576 g Sulfate / 1 mole sulfate)= 0.0859 grams SO₄^2-

---------------------------

Part A) Approximately how many mL of 5% BaCl2 solution would be required to precipitate all the sulfate if we assume that your samples are pure Magnesium sulfate? Assume that the density of the barium chloride solution is 1.00 g/mL.

Part B) If the samples were pure potassium sulfate would you require a smaller or larger volume of barium chloride solution than the amount calculated in (Part A) above?

B. Which member of the following pairs has the lesser predicted amount of entropy?

H2O (l) or H2O (s)

PbS (s) or PbF2(s)

Fe(s) at 25°C or Fe(s) at 100°C

1. For each of the following reactions, indicate whether you would expect the entropy of the system to increase or decrease, and explain why. If you cannot tell just by inspecting the equation, explain why.

a.CH₃OH(l) CH₃OH(g)

b.N₂O₄(g) 2NO₂(g)

c. CO(g) + H₂O(g) CO₂(g) + H₂(g)

d.2KClO₃(s) 2KCl(s) + 3O₂ (g)

e.2NH₃(g) + H₂SO₄(aq) (NH₄)₂SO₄(aq)

2. Predict which of the following reactions has a positive entropy change.

I. 2 N₂(g) + O₂(g) à 2 N₂O(g)

II. CaCO₃(s) à CaO(s) + CO₂(g)

III. Zn(s) + 2 HCl(aq) à ZnCl₂(aq) + H₂(g)

Consider the reacton of bromine and chlorine gas to form BrCl where Kp=1.11X10^-4 at 150K. A reaction mixture initially contains a bromine partial pressure of 755 torr and a chlorine partial pressure of 735torr at 150K. Calculate the equilibrium partial pressure of BrCl at 25^oC

In the reduction of benzil, three isomers of hydrobenzoin were produced. Despite the fact that all three isomers were produced in the lab, you only isolated the meso isomer. What happened to the 1R,2R, the 1S,2S isomers?

if mixture is composed of 76.3% c-12 and 23.7% of c-14 what is the average atomic mass

The equilibrium constant, Kc, for the following reaction is 1.05×10-3 at 446 K. PCl5(g) PCl3(g) + Cl2(g) When a sufficiently large sample of PCl5(g) is introduced into an evacuated vessel at 446 K, the equilibrium concentration of Cl2(g) is found to be 0.498 M. Calculate the concentration of PCl5 in the equilibrium mixture. ____M _______________________________________________________________________________________________________________ A student ran the following reaction in the laboratory at 689 K: N2(g) + 3H2(g) 2NH3(g) When she introduced 4.06×10-2 moles of N2(g) and 5.20×10-2 moles of H2(g) into a 1.00 liter container, she found the equilibrium concentration of H2(g) to be 5.00×10-2 M. Calculate the equilibrium constant, Kc, she obtained for this reaction. Kc = _______________________________________________________________________________________________________________________________ A student ran the following reaction in the laboratory at 658 K: 2NH3(g) N2(g) + 3H2(g) When she introduced 8.28×10-2 moles of NH3(g) into a 1.00 liter container, she found the equilibrium concentration of NH3(g) to be 6.82×10-3 M. Calculate the equilibrium constant, Kc, she obtained for this reaction. Kc =

Suppose that a student collects the following spectrophotometric data to determine the relative concentrations of HMR and MR in solution: The abosorbance at 425 nm was measured to be 0.320 and at 520 nm was 0.600, the slopes corresponding to standard Beer's Law plots were as follows:

?IA = 0.072   ?IIA = 0.760

?IB = 0.306 ?IIB = 0.036

Using this data, calculate the ratio between the relative concentrations of MR- and HMR in this solution.