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 ?

Hi,

I have some Organic Chemistry lab questions that I'm stuck on. Please explain in complete sentences

Thanks in advance

1. Describe the likely cuase and a reasonable solution for each problem encountered:

A. After spotting and developing a TLC plate, no spots are observed.

B. After spotting and developing a TLC plate, all spots moved along with the solvent front.

C. After spotting and develping a TLC plate, all spots are observed at the starting line.

2. What conclusion is justified if two substances rise at different rates on the same plate in the same solvent? What conclusion is justified if the two substances rise at the same level.

3. How can the R_F value be adjusted?

Peak intensity from a mass spectrum gives you what information about a compound?

-The relative abundance of each ion proportional to the most intense (base) peak

-The mass of each fragment

-The total number of atoms present in each fragment

-The number of different isotopic forms present

-None of the answers shown are correct

When speaking of a chemical reaction, what is a transition state?

-It is the lowest energy form of a product from an exothermic reaction

-It is the conversion of a substance from one physical state to another

-It is the difference in energy between a reactant to a product

-It is a temporary, unstable, but high energy form of a molecule with partial bonds

1. Balance the following oxidation-reduction reactions using the half-reaction method and tell the number of electrons transferred in the balanced oxidation-reduction reaction

a) S^2-(aq) + NO₃^-(aq) ---> S₈(s) + NO₂(g) acidic solution

b) MnO₄^-(aq) + I^-(aq) ---> MnO₂(s) + IO₃^-(aq) basic solution

c) Sb(s) + H₂SO₄(aq) ---> Sb₂(SO₄)₃(s) + SO₂(g) acidic solution

d) H₂O₂(aq) + MnO₄^-(aq) ---> MnO₂(s) + O₂(g) basic solution

Calculate the pH at 25°C of a 0.73M solution of potassium cyanide KCN . Note that hydrocyanic acid HCN is a weak acid with a pKa of 9.21 .

Based on gas chromatography results, predict the approximate retention times that probably would be obtained for the following compounds, and explain your predictions. (Compare the boiling points and intermolecular forces for each compound.)
3-Methyl-2-butanone (CAS Reg. No. 563-80-4)

What is the molar solubility of iron(III) hydroxide (Ksp = 2.5 x 10^-39) in water at 25

In a constant-pressure calorimeter, 60.0 mL of 0.320 M Ba(OH)2 was added to 60.0 mL of 0.640 M HCl. The reaction caused the temperature of the solution to rise from 21.70 °C to 26.06 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4.184 J/g·K, respectively), what is ΔH for this reaction (per mole of H2O produced)? Assume that the total volume is the sum of the individual volumes.