Calculate ΔHrxn for the following reaction:

CaO(s)+CO2(g)→CaCO3(s)

Use the following reactions and given ΔH values: Ca(s)+CO2(g)+12O2(g)→CaCO3(s), ΔH= -812.8 kJ

2Ca(s)+O2(g)→2CaO(s), ΔH= -1269.8 kJ

Express your answer using four significant figures.

what is the degree of polymerization (DP) of LDPE having an average molecular weight (mass) of 27,980?

Zinc metal reacts with hydrochloric acid according to the following balanced equation. Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g) When 0.107 g of Zn(s) is combined with enough HCl to make 54.9 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.0 ∘C to 24.0 ∘C.

Find ΔHrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/g⋅∘C as the specific heat capacity.)

Calculate the pH of the following solutions.

A.) 0.36 M NH4NO3

B)0.50 M Ca(NO3)2

C.)0.080 M C6H5NH2

D.) 0.45 M KNO2

5. Suggest 5 ways that the concentration of PH₃ could be increased in the following reaction.

P_{4 (g)} + 6 H_{2 (g)} ⇌ 4 PH_{3 (g)}        ΔH^o = 110 kJ/mol

6. Gaseous nitrogen dioxide forms gaseous dinitrogen tetroxide with a k_eq = 164 at 25°C in a 2.00L container

            a. Write and balance the equation

b. If at a given timepoint the concentrations of nitrogen dioxide was measured to be 0.500 M and the concentration of dinitrogen tetroxide was measured to be 1.25 M, is the reaction at equilibrium?

            c. What are the concentrations at equilibrium?

d. After the initial equilibrium, if 5.00mol of dinitrogen tetroxide was introduced into the container, what are the concentrations of both species when equilibrium reestablishes?

Which of the following reactions is/are redox reactions?  You may select more than one reaction.

In the body, mercury's toxic effects are known to result from its ability to disrupt and insert into S-S bonds in critical enzymes. Fish, particularly tuna, which contain high levels of methylmercury are frequently found to also have high levels of selenium. Given the low rate of mercury poisoning even in populations where large quantities of fish are consumed, this has led some to speculate that selenium serves to protect against mercury poisoning. Explain the chemical basis for this theory

An industrial wastewater contains a total cyanide concentration of 10-3M and a total nickel concentration of 210-4M. Calculate the concentrationof all species (HCN, CN-, Ni2+, and all cyanide and hydroxy complexes of nickel) at pH 9.0. State and verify all assumptions.

A pH 3.30 buffer is prepared from iodoacetic acid ICH₂COOH (pK_a = 3.175), and sodium iodoacetate, ICH₂COO^-Na⁺ . If ionic strength of the buffer solution must not exceed 0.200 M, what are the maximum concentrations of the two components that could be used?

What volume of KOH (conc = 1.850 M), could be added to 50.00 mL of the buffer solution of part (a), before the pH would increase to 4.000?

1. Compare the advantages and disadvantages of each pH method (i.e. cost, ease of use- time it takes to set up and take a pH measurement) including accuracy and precision of each method.

2. draw a diagram labeling the two silver/ silver chloride reference electrodes, glass membrane, and porous frit.

3. show how a charge is built up and produces a voltage that is measured.

Suppose that a student collects the following spectrophotometric data to determine the relative concentrations of HMR and MR in solution:

The abosorbance at 425 nm was measured to be 0.280 and at 520 nm was 0.720, the slopes corresponding to standard Beer's Law plots were as follows:

Using this data, calculate the ratio between the relative concentrations of MR^- and HMR in this solution.

You are trying to establish the IgG response from a recently vaccinated individual, where it will be important to know how much IgG they have both before and after the vaccination. You start with two samples of 8 mL of blood, one from before vaccination and one after. You use an affinity chromatography technique to remove just the IgG (ε = 1.35 g-1L cm-1). You end with a 2 mL sample of each. The pre-vaccinated sample has an A280 reading of 0.85, and the post-vaccinated sample has an A280 reading of 0.202 with a 10-fold dilution (both with a 1 cm path length).

a) How many micrograms of IgG were in each of the original blood samples?

b) What fold change in IgG amounts was seen after vaccination?

You have evaluated the theoretical pI of Our Protein Of Interest (OPOI), based on its amino acid sequence, to be 6.4. You select a working pH of 8.0 and will use what type of ion exchange?______________________________

A sample of 10.00 g of sodium reacts with oxygen to form 15.02 g of sodium oxide (Na₂O) and sodium peroxide (Na₂O₂). Calculate the percent composition of the mixture.

___% Na₂O

___% Na₂O₂

You purified the plasmid from an overnight cell culture and dissolved the plasmid DNA in 100 μL 0.1M Tris buffer (pH8). To quantify the plasmid, you took an absorbance measurement at 260 nm of a 1:50 dilution sample. The absorbance was 0.35. What is the concentration of the undiluted plasmid in micrograms per mL?