#3 R&D Exp. 26

Should Cu(OH)₂ precipitate in 3 M NH₃ if the original [Cu²⁺] is 0.1 M ( the K_b for ammonia is 1.6x10^-5)?

Please show work and explain a little of how you got this result

Calculate the pH of each of the following strong acid solutions.
(a) 0.00512 M HBr

pH =  

(b) 0.633 g of HI in 18.0 L of solution

pH =  

(c) 44.0 mL of 3.90 M HBr diluted to 1.30 L

pH =  

(d) a mixture formed by adding 89.0 mL of 0.00215 M HBr to 89.0 mL of 0.000310 M HI

pH =  

Assuming 100% dissociation, calculate the freezing point and boiling point of 2.79 m K3PO4(aq). Constants may be found here.

Identify the incorrect statement

A) At equilibrium the concentration of the rectants is equal to the concentration of the products

B) A change in temp will change the value of the equilibrium constant

C) Removing reactants from a system at equilibrium shifts the reaction left

D) Decreasing the pressure of a system at equilibrium shifts the reaction tward the side with the most gas molecules

E) All of the above are correct

Please explain how you got your answer

Can anyone explain the complete mechanism of a nitrile with a grignard reagent to form a ketone?

1. Write the solubility equilibrium and the solubility product expression for the following sparingly soluble salts.

CaCO3

Cu2S

Sb2S3

2. The solubility of silver bromide, AgBr, at 25

Here are some problems and their answers. I would appreciate if someone could please explain step by step how to get these answers? I need to understand this concept.

The following questions refer to the equilibria: 2 NaHCO3(s) ⇌ Na2CO3(s) + H2O(g) + CO2(g) K(110°C)=0.68

1)If CO2(g) is added to the equilibrium mixture the partial pressure of H2O(g) will: answer: Decrease (how and why??)

2) If the volume of the container is decreased, the amount in grams of sodium carbonate (Na2CO3(s)) will: Answer: decrease (I thought volume only affects gases??)

3)The ΔH of the reaction was measured and determined to be -25 kJ/mole of sodium bicarbonate (NaHCO3). If the reaction were run at 150°C, a possible value for K could be: answer: 0.54

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This next question is not involved with the above.

4) What is the pH of the solution after 30 mL of 0.12 M HCl is mixed with 60 mL of 0.12M NaOH? Answer: . 12.60

which species will have the greatest absolute entropy at 25 degrees celcius Ne (g),
C2H2(g)
Ne (g)

H2O(l)
C2H5OH (l)
C4H10 (g)

thanks

How would you do the problem... What is the concentration in mmole/L of a Ca2+ solution that is 2.10 mEq/L ?

I recall on more than one occasion when our kids were small, we would come inside from playing in the snow and I would make hot chocolate by heating the milk in the microwave. Invariably, I would get the milk too hot for at least one of them. Rather than adding more cold milk to the hot chocolate, I dropped a couple of small ice cubes into the mug. I figured they would never notice the dilution effect that the water had on the hot chocolate since they always enjoyed adding about thirty marshmallows to the mixture after I served it to them anyway.

Although I never actually took any temperatures of the hot chocolate, let’s assume that the initial temperature was 175⁰F and the mug contained 350 g of hot chocolate.

a)   If the initial temperature of the hot chocolate was is 175⁰F, what would the temperature of the drink be once the ice cubes had completely melted and the mixture stirred? Express your answer in “degrees Celsius” to one decimal place. Since the marshmallows were added after I served the drinks, they would have no impact on the temperature of the drink at the time I served it. Additional information is provided below.

b)   From a purely personal perspective (i.e., in your own opinion), would you consider the chocolate milk still be too hot for you personally to drink or would it be a bit on the cool side? How can you support your answer?  

Additional information:

Weight of ice cubes   =   75 grams total weight
Initial temperature of ice cubes   =   - 18⁰C
Specific heat capacity of the hot chocolate   =   3.751 kJ/kg C⁰

Hints: While this problem can be a little bit “scary” at first, it should not really be that bad if you break the problem down into a series of more manageable steps. Think about what is happening before you charge ahead and start trying to actually solve this problem.  

You can simplify things greatly if you draw a diagram to represent what is happening. Draw a vertical line to represent a “thermometer” and mark the important points on it (this diagram will also assist you in determining the temperature changes etc.). These points will include the starting temperatures of the chocolate milk and the ice as well as the freezing / melting point of the ice.  

Let the final temperature of the thawed ice and milk be X (the chocolate milk and the melted ice will both have the same final temperature since they are mixed together in the same mug). X will be somewhere between the thawing / freezing point of the ice and the initial temperature of the milk - the trick is to find out what the temperature actually is. Remember that the heat lost by the milk will be equal to the heat gained by the ice, if we assume that no heat is lost to the surroundings (which we will do in this case).

show me step by step calculations on enthalpy of formation of hydrogen peroxide

A galvanic cell (battery) is represented by the shorthand below. Look up the standard half cell potentials in your textbook or on the internet. (Make sure you select the half reactions that have all the species required, and no other species.)

            Cd(s) / Cd²⁺ // IO₃^- , H+, Cl^-, ICl₂^- / Pt(s)

(a) Calculate E^o for this battery.

(b) What is the oxidizing agent (chemical formula of the species, not just the element)?

What is the reducing agent (chemical formula of the species, not just the element)?

            What species is/are found in the cathode compartment?

(c) Determine the overall balanced chemical equation for the battery reaction.

(d) Use Nernst eqn and the concentrations below, calculate expected cell potential.

[Cd²⁺] = 0.0250 M     [IO₃^-] = 0.100     pH = 4.00      [Cl^-] = 0.500 M        [ICl₂^-] = 1.75 x 10^-5 M

1. When crotyl chloride is treated with sodium iodide in acetone, it reacts much faster than n-butyl chloride, even though both are primary alkyl halides. Explain the rate difference.

2.The most significant difference between the S_N1 and S_N2 mechanism is the _______________ intermediate that is formed in an ______ mechanism.

3. List butyl chloride, sec-butyl chloride, and tert-butyl chloride in order of increasing relative reactivity with ethanolic AgNO­₃. Explain the reason one might expect these results.

4. Why should n-butyl bromide react faster than n-butyl chloride ?