How much heat is required to convert solid ice with a mass of 605 g and at a temperature of -12.5 °C to liquid water at a temperature of 55.5 °C? (The specific heat of ice is c_ice = 2100 J/kgK, the specific heat of water is c_water = 4186.8 J/kgK, and the heat of fusion for water is: L_f = 334 kJ/kg.)

1. A student prepares two aqueous solutions. For each solution:

-Calculate the molarity.

-Write a chemical equation representing the formation of the solution. Be sure to include phase labels and to show any ions that dissociate.

-Draw a molecular picture of the solution showing any ions, solute molecules and water molecules.

A. 2.91 g Na₂CO₃ to make 25.0 mL solution.

B. 6.14 mL ethanol (d=0.789 g/mL) to make 75.0 mL of solution.

C. Which solution is more concentrated?

D. Identify each solution as a strong, weak, or non-electrolyte.

nitrogen and hydrogen combine at high temperature, in the presence of a catalyst, to produce ammonia. N2(g)+3H2(g) > 2NH3(g). assume 0.270 mol of N2 and 0.877 mol of H2 are present initially. Questions- 1. after complete reaction, how many moles of ammonia are produced? 2. how many moles of H2 remain? 3. how many moles of N2 remain? 4. what is the limiting reactant(hydrogen or nitrogen)?

1. The effect of an inhibitor on an enzyme was tested and the experiment gave the results below. Plot on Excel the data using a double-reciprocal plot (Lineweaver-Burke), determine K_m and V_max of the no inhibitor and each type of inhibitor and the type of inhibition that is occurring.

[S] µM      V (µmol/min) V (µmol/min) V (µmol/min)

                  with 0.0 nM    with 25 nM     with 50 nM

                  Inhibitor          Inhibitor          Inhibitor

______      ___________ ___________ ___________

                     0.4          0.22                0.21                 0.20

                     0.67        0.29                0.26                 0.24

                     1.00        0.32                0.30                 0.28

                     2.00        0.40                0.36                 0.32

Draw the electron-group geometry for HNO3, in which hydrogen is attached to one of the oxygens and all oxygens are attached to nitrogen. To simplify, ignore the hydrogen when you name the molecule's shape. Draw the Lewis dot structure.

Consider the following reaction:

2 Al + 3 CuCl₂ → 3 Cu + 2 AlCl₃

The reaction begins with 83.16 g of Al and 49.19 g of copper II chloride.

How much of the excess reactant is left behind (unused)?  g

How many grams of Cu is produced:  g

How many grams of AlCl₃ is produced:  g

A solution is found to be 0.0404% by weight CoBr₃. What is the concentration of the Br^1- ion expressed in ppm?

Consider this reaction:

2CH₃OH(l) + 3O₂(g)₂O(l) + 2CO₂(g) H = –1452.8 kJ/mol

a.Is this reaction endothermic or exothermic?

b.H if the equation is multiplied throughout by 2?

c.H if the direction of the reaction is reversed so that the products become the reactants and vice versa?

What is the value of ∆H if water vapor instead of liquid water is formed as the product?

1.Draw a Lewis structure for each of them. Remember that some molecules violate the Octet Rule in different ways. Some of these use multiple bonds and some don't. You need to figure out which do. Use the rules we had in class for writing Lewis structures and compare with these with the molecules we did write Lewis structures for. None of these have resonance structures.

SF₆ CH₄ I₃^- N₂    XeF₄ NH₃ OH^- CO C₂H₄ (in this molecule there is no one central atom, the two carbons are bonded together and in addition each carbon bonds with two hydrogen atoms)

2.Draw a Lewis structure for each of the following. For two of these molecules there are resonance structures. See if you can identify which two they are and draw the resonance structures.

NF₃ NO₃^-   O₂ SO₂ NO⁺ PCl₃ F₂ HCl OF₂ IF

student is asked to standardize a solution of calcium hydroxide. He weighs out 0.993 g potassium hydrogen phthalate (KHC8H4O4, treat this as a monoprotic acid). It requires 20.1 mL of calcium hydroxide to reach the endpoint.

A What is the molarity of the calcium hydroxide solution?

This calcium hydroxide solution is then used to titrate an unknown solution of hydroiodic acid.

B. If 25.5 mL of the calcium hydroxide solution is required to neutralize 15.0 mL of hydroiodic acid, what is the molarity of the hydroiodic acid solution? M

Estimate the pH of a 25o C solution of both ammonium chloride, NH₄Cl, and acetic acid in water, at a concentration of 0.10 M, each.

How would Acetic Acid, HC2H3O2 and Sodium Acetate, NaC2H3O2 work as a buffer? Explain with equations.

Separation techniques were performed on a sample containing only sand and salt. The mass of the initial sample was 10.50 g. After the separation, 3.10 g of sand and 4.00 g of salt were recovered. What is the percent recovery of sand and salt?

1. What volume of 0.158 M HCl is required to neutralize 2.87 grams of Mg(OH)2?

2. Which ion(s) is/are spectator ions in the formation of a precipitate of BaSO4, when aqueous solutions of BaI2 and K2SO4 are mixed?