Identify the molecular geometry for each of the following triatomic molecules using the VSEPR model. Then, determine which molecules would be expected to have at least one normal mode that is infrared active. Explain your reasoning

a. NO2

b. PCl2 +

c. BrF2 -

d. N3 -

What is the percent yield of the solid product when 12.01 g of iron(III) nitrate reacts in solution with excess sodium phosphate and 5.008 g of the precipitate is experimentally obtained?

Fe(NO₃)₃(aq) + Na₃PO₄(aq) --> FePO₄(s) + NaNO₃(aq) [unbalanced]

A 30.00-mL solution of HBr was treated with 5 mL of freshly boiled and cooled 8 M HNO3, and then with 50.00 mL of 0.3650 M AgNO3 with virgorous stirring. Then 1 mL of saturated ferric alum was added and the solution was titrated with .2870 M KSCN. When 3.60 mL had been added, the solution turned red. What was the concentration of HBr in the origninal solution? How many millimgrams of Br- were in the original solution?

Mg(OH)2 is a sparingly soluble salt with a solubility product, Ksp, of 5.61×10−11. It is used to control the pH and provide nutrients in the biological (microbial) treatment of municipal wastewater streams. What is the ratio of solubility of Mg(OH)2 dissolved in pure H2O to Mg(OH)2dissolved in a 0.160 M NaOH solution?

Express your answer numerically as the ratio of molar solubility in H2O to the molar solubility in NaOH.

How many milliliters of a 1% w/v epinephrine injection must be used to prepare 20 mL of an injection containing 1:200,000 w/v epinephrine?

Chemical cold packs used for sports injuries are made with solid ammonium nitrate (NH4NO3) and a plastic bag of water. When the bag of water is broken the ammonium nitrate dissolves.

NH4NO3(s) --> NH4+ (aq) + NO3- (aq)

As the solution forms, the water and bag get colder.

Which of the following is true for this process. ( Assume the reaction above is our system) Chose all that apply

Select one or more:

a. The process is endothermic.

b. Δ H for the reaction is positive

c. q for the water is positive.

d. The process is exothermic.

e. The solid ammonium nitrate has more enthalpy (H) than the ammonium and nitrate ions.

f. q for the water is negative.

g. The solid ammonium nitrate has less enthalpy (H) than the ammonium and nitrate ions.

h. q for the reaction is negative.

i. q for the reaction is positive.

A.) In yeast, ethanol is produced from glucose under anaerobic conditions. What is the maximum amount of ethanol (in millimoles) that could theoretically be produced under the following conditions? A cell-free yeast extract is placed in a solution that contains 325 mmol glucose, 0.35 mmol ADP, 0.35 mmol Pi, 0.70 mmol ATP, 0.20 mmol NAD , and 0.20 mmol NADH. It is kept under anaerobic conditions. (answer in mmol)

B.) Under the same conditions, what is the theoretical minimum amount of glucose (in millimoles) required in the solution to form the maximum amount of ethanol? (answer in mmol)

What are two other methods to extract essential oils apart from steam distillation? Describe each.

Calculate the equilibrium compositions due to the decomposition of 1 mole of nitrogen tetroxide at 25C and 1 bar in each of the following cases.

N2O4(g) <==> 2NO2(g)   

N2O4  : ΔHf (formation) = 9160 joules/mole and ΔGf (formation) = 97540 joules/mole at 298 K

NO2 :   ΔHf (formation) = 33180 joules/mole and ΔGf (formation) = 51310 joules/mole at 298 K of

a.) Use the reaction equilibrium method with extent of reaction ξ, and let the initial state be pure N2O4.

b.) Use the reaction equilibrium method with extent of reaction ξ, and let the initial state be 1 mole inert Argon in addition to 1 mole of N2O4.

PCR;

4. A student is using the following PCR cycle conditions to amplify a 384 bp segment of DNA:

i) incubate at 95^oC for 30 seconds;

ii) incubate at 53^oC for 30 seconds;

iii) incubate at 72^oC for 40 seconds.

(a) Describe what is happening during each step (i, ii, iii) of the PCR cycle.

(b) After gel electrophoresis of the PCR products, the students see three bands (212 bp, 288 bp, 866 bp) in addition to the desired 384 bp product. Which PCR step (i, ii, iii) should be modified, and how, to try and amplify only the desired 384 bp band? Explain.

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 0.260 and at 520 nm was 0.880, 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.

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

As background, an antacid contains an unknown number of milligrams (mg) of CaCO3 per 2.0 g tablet according to the label. (CaCO3: 100.09 g/mol). Based on the questions below, determine the mg of CaCO3 in the 2.0 g tablet. The reaction by which the antacid neutralizes HCl is 2 HCl(aq) + CaCO3(s) --> CaCl2(aq) + CO2(g) + H2O(l) Q1: How many moles of HCl are neutralized by one mole of CaCO3(s)? ___ mol Q2: 50.0 mL of 0.300 M HCl are added to an Erlenmeyer flask containing a 2.00 g antacid tablet. Calculate the moles of acid in the 50.0 mL of 0.300 M HCl? ___ mol Q3: A student fills her burette with NaOH to the 2.5 mL mark. She titrates her sample of the NaOH until she reaches the endpoint (i.e. all the acid has been neutralized by the NaOH). The volume marking on her burette - at the endpoint - is 52.5 mL. How many mL of NaOH did she use to reach the endpoint? Q4: Some of the 2.0 g of antacid neutralizes the HCl. However, there is excess acid, not neutralized by the antacid. To determine the excess moles of acid, a student used 50.00 mL of 0.100 M NaOH to titrate the excess acid. How many moles of excess acid are there? ___ mol HCl Q5: How many moles of HCl were neutralized by the 2.0 g antacid tablet? ___ mol Q6: How many mg of CaCO3 were in the original 2.00 g tablet? ___ mg

The stoichiometric relationship between the reactants and products of an aqueous reaction can be used to determine different kinds of information about a reaction, such as the volume of a given molarity reactant required to produce a certain amount of product.

Hydrochloric acid (HCl) reacts with sodium carbonate (Na2CO3), forming sodium chloride (NaCl), water (H2O), and carbon dioxide (CO2). This equation is balanced as written:

2HCl(aq)+Na2CO3(aq)→2NaCl(aq)+H2O(l)+CO2(g)

------------------------------------------------------------------------------------------------------

a) What volume of 2.00 M HCl in liters is needed to react completely (with nothing left over) with 0.250 L of 0.300 M Na2CO3?

Express your answer numerically in liters.

--------------------------------------------------------------------------------------------------

b) A 373-mL sample of unknown HCl solution reacts completely with Na2CO3 to form 19.1 g CO2. What was the concentration of the HCl solution?

Express the molar concentration numerically.