hillary duff

1.Calculate the potential of the following electrochemical cell:

Ag/AgCl (s) /AgCl (sat), HCl (0.0100 M)//HCl (analyte, 0.0020 M)/H2 (0.800 atm)/Pt

Determine the change in cell potential that would be expected if the analyte HCl concentration were changed from 0.0020 M to 0.0200 M.

2. The cell:

SCE // H + (a = x) / glass electrode

has a potential of +0.2094 V when the solution in the right-hand compartment is a buffer of pH 4.006. The following potentials are obtained when the buffer is replaced by unknowns: (a) -0.2910 V and (b) +0.2011 V. Calculate the pH and the hydrogen ion activity of each unknown.

1. Separate these redox reactions into their two component half-reactions. Balance the half-reactions by supplying e, H+ and H2O as needed, then determine the balanced overall reaction:

(a) MnO4 - + VO 2+ = Mn 2+ + V(OH)4 +

(b) Cr2O7 2- + U4+ = Cr 3+ + UO2 2+

(c) IO3 - + I - = I2 (aq)

(d) HPO3 2- + MnO4 - + OH - = PO4 3- + MnO4 2-

1. masses of solid tris and tris HCl( Tris= tris(hydroxymethyl)aminomthane) should be combined and diluted to 100mL to make a 0.100M buffer with ph = 7.40?

convert the following:

8.4g/L NaCl into mM

3.16*10^-6 M Fe2+ into ppm

6.30 mM glucose into mg/dL

5.0 ppm Ca2+ into muM

1. Calculate the value of E°cell for a voltaic cell described in each of the following.

a. F2(g) is reduced to F−(aq) and Fe(s) is oxidized to Fe2+(aq).

b. Cu2+(aq) is displaced from solution by Zn(s).

c. The cell reaction is 2Cu+(aq)-->Cu2(aq)+Cu(s)

d. MgBr2(aq) is produced from Mg(s) and Br2(l).

1. What is the pH of a saturated solution of Mg(OH)2 at 25oC? For Mg(OH)2, Ksp=7.1x10-12.

2.

a. [Cu2+] remaining in 444 mL of a solution that was originally 0.742 M CuSO4, after passage of 2.61 A for 261 s and the deposition of Cu at the cathode.

b.The time required to reduce [Ag+] in 153 mL of AgNO3(aq) from 0.192 to 0.121 M by electrolyzing the solution between Pt electrodes with a current of 4.72 A.

1. How many moles of NaOH must be added to 0.400 L of 0.189 mol/L HF(aq) to obtain a solution with pH=3.4? Assume the temperature is 25oC. (For HF, pKa=3.18 at 25oC).

2. What is the pH at the equivalence point when when 40.0 mL of 0.189 mol/L HC3H5O2(aq) is titrated with 0.121 mol/L NaOH(aq)? Assume the temperature is 25oC. (For HC3H5O2, pKa=4.89 at 25oC).

3. If 75.0 mL of 0.117 mol/L NaOH(aq) and 45.0 mL of 0.183 mol/L HA(aq) are mixed, then what is [HA] at equilibrium? Assume that HA is a weak monoprotic acid with pKa=6.01 at 25oC.

1. Which of the following substances has the largest value for Ka,1?

NH3

SiH4

H2Se

CH4

AsH3

H2S

i know it's not Nh3 and H2s but which one is it?

1. What is the enthalpy change, in Kj/mol, for the process below?

Ca^2+ (g) + 2Cl^- (g) --> CaCl2 (s)

Data (in kJ/mol):

Enthalpy of sublimation of Ca(s): 178

Bond dissociation energy of Cl2(g): 244

Ionization energies (1st, 2nd, 3rd) of Ca(g): 590; 1,145; 4,912

Ionization energies (1st, 2nd, 3rd) of Cl(g): 1,252; 2,297; 3,822

First electron affinity of Cl(g): -349

Standard enthalpy of formation for CaCl2(s): -796

2. Two elements, X and Y, form a crystalline material. The crystal lattice of this material can be described as follows. The X atoms form a cubic closest packed structure and the Y atoms occupy half of the tetrahedral sites in the lattice of X atoms.

The empirical formula of the solid is: X ____ Y ____

1. For a given liquid, the enthalpy of vaporization is 31.81 KJ/mol and the boiling point at 1 atm is 97.14C. what is the vapour pressure of the liquid at 32C?

2. For a given liquid, the enthalpy of vaporization is 32.6 KJ/mol and the vapour pressure is 107 torr at 25C. what is the boiling point of the liquid at 1 atm?

3. Identical hard spheres of radius R are packed together to form a simple cubic lattie. What is the ratio a/R, where a is the edge length of the unit cell?

4.An unidentified metal crystallizes in a body-centered cubic lattice with an edge length of 287 pm. The density of the metal is found to be 7.85 g/cm^3. What is the identity of the metal?

please explain in steps.

1. An unidentified element crystallizes in a face-centred cubic lattice. The edge length of the unit cell is 446 pm/ The density of the solid is found to be 1.51g/cm^3. What is the molar mass of the elemnet, in g /mol?

2. What is the enthalpy change, in Kj/mol, for the process below?

Ca^2+ (g) + 2Cl^- (g) --> CaCl2 (s)

Data (in kJ/mol):

Enthalpy of sublimation of Ca(s): 178

Bond dissociation energy of Cl2(g): 244

Ionization energies (1st, 2nd, 3rd) of Ca(g): 590; 1,145; 4,912

Ionization energies (1st, 2nd, 3rd) of Cl(g): 1,252; 2,297; 3,822

First electron affinity of Cl(g): -349

Standard enthalpy of formation for CaCl2(s): -796

3. Two elements, X and Y, form a crystalline material. The crystal lattice of this material can be described as follows. The X atoms form a cubic closest packed structure and the Y atoms occupy half of the tetrahedral sites in the lattice of X atoms.

The empirical formula of the solid is: X ____ Y ____

4. Which of the following compounds has the lowest boiling point?

(a) H2O

(b) CH3COOH

(c) CH3CH2CH2NH2

(d) H3C-O-CH2CH3

(e) CH3CH2CH2OH

please explain in steps.

1. For a given liquid, the enthalpy of vaporization is 31.81 KJ/mol and the boiling point at 1 atm is 97.14C. what is the vapour pressure of the liquid at 32C?

2. For a given liquid, the enthalpy of vaporization is 32.6 KJ/mol and the vapour pressure is 107 torr at 25C. what is the boiling point of the liquid at 1 atm?

3. Identical hard spheres of radius R are packed together to form a simple cubic lattie. What is the ratio a/R, where a is the edge length of the unit cell?

4.An unidentified metal crystallizes in a body-centered cubic lattice with an edge length of 287 pm. The density of the metal is found to be 7.85 g/cm^3. What is the identity of the metal?

please explain in steps.

1. A particle moves along the x-axis from x = 0 to x = 10, and is subject to a force field

given by F(x) = 2 + cos((pi/5) x)

The work done by the field is thus W =

integration 0 -10F(x)dx.

a) Approximate W using the left and right Riemann sums with 4 subdivisions, i.e.

using L4 and R4.

b) Explain, using a geometrical argument, why each of these actually give you the

exact value of W.

c) Confirm your value of W using the Fundamental Theorem of Calculus.

2. A circular disk of radius r is used in an evaporator and is rotated in a vertical plane. If

it is to be partially submerged in the liquid so as to maximize the exposed wetted area

of the disk, show that the center of the disk should be positioned at a height r/(sqrt(1+pi^2)) above the surface of the liquid.

A 0.007049-mol sample of an organic compound was burned in oxygen in a bomb calorimeter. The temperature of the calorimeter increased from 24.7oC to 26.9oC. If the heat capacity of the calorimeter is 4.36 kJ (oC)-1, then what is the constant volume heat of combustion of this compound, in kilojoules per mole? (Remember to include a "+" or "-" sign in your answer, as appropriate.)

explain in steps pleasee

1. What is the average oxidation number (i.e. oxidation state) of oxygen in OF2?

Important: If the oxidation number is fractional, enter your answer as a fraction, not as a decimal number (e.g. enter 1/2, 1/3, 1/4, 2/3, etc. not 0.5, 0.33, 0.25, 0.67, etc.)

2.

A 3.923-g sample of a mixture of Mg and Al is treated with excess HCl(aq). If 0.1940 moles of H2 are obtained, then what is the percentage by mass of Mg in the original mixture? Give your answer accurate to three significant figures. Do not include the % sign in your answer!

Reactions:

Mg(s) + 2 HCl(aq) --> MgCl2(aq) + H2(g)

2 Al(s) + 6 HCl(aq) --> 2 AlCl3(aq) + 3 H2(g)

1. A 3.6186-g sample of a hydrate of Hg(NO3)2 was heated to drive off all of the water of hydration. The remaining solid weighed 3.4283 g. If Hg(NO3)2.x H2O represents the formula of the hydrate, then what is the value of x?

2. Complete combustion of 2.496 g of a particular hydrocarbon yielded 7.306 g CO 2 and 4.486 g of H 2 O. What is the empirical formula of this hydrocarbon?

steps pleaee

The max function is a function of 2 variables and is defined as follows: max (a,b) = [a if a>=b ..b if a <b]...express this piecewise-defined function in one line using the absolute value function.

suppose that a car consumes gas according to the equation f(v) =(v-10)^2 + 9900 where v is its speed in km/hr and f(v) is the fuel consumption rate inml/hr. Find the speed that gives the best fuel economy,i.e., the best distance-to-fuel-ratio. hinti: the idea is to minimize fuel per unit distance not per unit time. think graphically.

consider the parabola y = (x-1)^2 + 1

1. find the values of x for which the line y=2x intersects this parabola.

2. find the value of m>0 for which the line y=mx touches this parabola at just one point.

MgCl2 often occurs in table salt (NaCl) and is responsible for cooking of the salt. A 0.5200g sample of table salt is found to certain 61.10% Cl by mass. What is the % of MgCl2?

please do it in steps

thannks