A sample of pure water was spiked with 0.670 ng/mL silver ion. Ten replicate determinations of the spiked water sample gave 0.680, 0.660, 0.637, 0.623, 0.664, 0.644, 0.648, 0.652, 0.630, and 0.615 ng/mL silver ion. Determine the mean percent recovery of the spike and the detection limit (in ng/mL) of the analytical method used for silver ion determination.

How can the volume of an irregular unknown object be measured?

using a ruler to measure length,

width, and depth measuring the volume of water displaced by the object

obtaining the mass of the object

measure the radius and use V= hr2

Consider the cell described below at 261 K:

Fe | Fe²⁺ (0.903 M) || Cd²⁺ (0.991 M) | Cd

Given E^o_Cd²⁺→Cd = -0.403 V, E^o_Fe²⁺→Fe = -0.441 V. Calculate the cell potential after the reaction has operated long enough for the Fe²⁺ to have changed by 0.373 mol/L

When 0.601 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 26.1 ∘C to 30.3 ∘C.

Find ΔErxn for the combustion of biphenyl in kJ/mol biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/∘C.

A block of copper, of unkown mass, initially at 75.7 celcius is immersed in a beaker containing 125.5 g of water at 20.7 celcius. At thermal equilibrium, the final temperature is 24.2 celcius. What is the mass of the copper if the specific heat capacities of water is 4.18 J/(gC) and copper is 0.385 J/(gC))

For the following reaction between Mohr\'s salt (iron as FeSO4(NH4)2SO4

The equilibrium constant, K, for the following reaction is 10.5 at 350 K.

2CH2Cl2(g) CH4(g) + CCl4(g)

An equilibrium mixture of the three gases in a 1.00 L flask at 350 K contains 5.09E-2 M CH2Cl2, 0.165 M CH4 and 0.165 M CCl4. What will be the concentrations of the three gases once equilibrium has been reestablished, if 3.82E-2 mol of CH2Cl2(g) is added to the flask?

[CH2Cl2]

=

M

[CH4]

=

M

[CCl4]

=

M

The equilibrium constant, K, for the following reaction is 1.29E-2 at 600 K.

COCl2(g) CO(g) + Cl2(g)

An equilibrium mixture of the three gases in a 1.00 L flask at 600 K contains 0.192 M COCl2, 4.98E-2 M CO and 4.98E-2 M Cl2. What will be the concentrations of the three gases once equilibrium has been reestablished, if 2.93E-2 mol of Cl2(g) is added to the flask?

[COCl2]

=

M

[CO]

=

M

[Cl2]

=

M

Let’s compare two monoprotic acids: one strong (nitric, HNO3, pKa = -1.60) and one weak (acetic, CH3COOH, pKa = 4.79).

a. [4 points] Sketch an alpha diagram for each of the acids.

b. [6 points] Use your alpha diagram to predict the percentage of undissociated acid for each at the following pH values: 0.1, 3, 4.3, 6, and 13. After estimating the fractions with your diagram, check your values by calculating the exact value.

c. [4 points] Explain the difference in pKa values (and the percentage dissociated in parts a and b) for nitric acid and acetic acid. In your explanation, include and underline the following terms: pH, H+ concentration, strong/weak acid, and Le Chatelier’s Principle.

Butane liquid and vapor coexist at 370.0K and 14.35 bar. The densities of the liquid and vapor phases are 8.128 mol-L^-1 and 0.6313 mol-L^-1, respectively. Use the van der Waals equation, the Redlich-Kwong equation, and the Peng-Robinson equation to calculate these densities. Take alpha = 16.44 bar-L^2-mol^-2 and beta = 0.07245 L-mol^-1 for the Peng-Robinson equation.

(Chapter 16, problem 24 in the Physical Chemistry, a molecular approach book)

1.) Chlorofluorocarbons (CFCs) were introduced as refrigerants in the 1930s, replacing other gases that were toxic and corrosive. How do the molecular shape and polarity of CFCs contribute to the many desirable qualities they have as refrigerants? Given that they are such desirable refrigerants, why are they banned? What chemistry is involved? How has their molecular shape and polarity had harmful effects on the atmosphere?

2. Chemically, how does soap work to remove grease? Give some other related examples.

Now that the acid has been standardized and you know it is 0.2496 M H2SO4, you perform the actual experiment as follows:

A 3.100-g sample of meat is subjected to Kjeldahl analysis. The liberated NH3(g) is absorbed by adding 50.00 mL of H2SO4(aq), which is more than enough. The excess acid requires 19.90 mL of 0.5510 M NaOH for its complete neutralization.
What is the percentage of protein in the meat?

Why is it important to measure the solutions from least concentrated to most concentrated in UV-Vis Spectroscopy?

For a particular redox reaction, ClO−2 is oxidized to ClO−4 and Fe3+ is reduced to Fe2+. Complete and balance the equation for this reaction in basic solution. Phases are optional.

Step by step please

BACK TITRATION OF ASCORBIC ACID

For the standardization, 5 ml of KIO₃ was added, as well as 0.5087 g of solid KI and 2.5 mL of 0.5 M H2SO4. It was titrated with the Na2S2O3 solution previously prepared.

0.01 M KIO3 (+excess KI and acid)           0.07 M Na2S2O3

1- Calculate the ascorbic acid concentration from your manual titration. (HOW TO CALCULATE THE EXCESS IODINE)

IO₃^- + 8I^- + 6H⁺ ?3I ₃^-+ 3H2 O                                

   I₃^- + 2S₂O₃^-2 ? 3I^- +S₄ O₆^-2        

C₆H₈O₆ + I₃^- ? C₆H₆O₇ + 4H⁺ +3I^-

Standardization of Thiosulfate solution

analysis of ascorbic acid

A 5.00ml volume of 0.20M solution contains 1.0mmol of solute. show the factor label calculation for why this statement is true.

Consider the titration of 0.1mmol of acetic acid in 25mL ( total volume) using 0.200M NaOH. assume Ka= 1.7 *10^-5

a) Calculate the total volume at the equivalence point.

b) calculate the acetate concentration at the equivalence point.

c) calculaye the theoretically expected pH at the equivalence point.

Please show work! Thanks!!!!