Discuss the relevance of of qualitative anaysis for metals in water (i.e. metals in aqeous soultions). For example, what is the usefullness of qualitative anaylysis and what use could such analyses of metal cations (or any other species) have that relates to our lives?

As with any combustion reaction, the products of combusting a hydrocarbon fuel (CxHy) with oxygen (O2) are carbon dioxide (CO2) and water (H2O).

A mass of 16.89 g for an unknown fuel was combusted in a reaction vessel containing an unknown amount of oxygen. At the end of the reaction, there still remained 16.85 g of the fuel as well as 0.0654 g of water and 0.1198 g of carbon dioxide. The oxygen was completely consumed during the reaction.

How many molecules of oxygen gas were initially present in the reaction vessel?

Express the number of molecules to three significant digits

Use the method of successive approximations to determine the pH and concentrations of H2A, HA–, and A2– in a solution of 0.00273 M monopotassium fumarate (KHA). The pKa values for fumaric acid are 3.02 (pKa1) and 4.48 (pKa2).

Of the original “undiluted” sample from Question 1(see below), 10L of a 5-to-1 dilution were used to measure protein concentration. With the use of a standard curve, this is found to be 140g. What is the specific activity of the original sample? Question 1 referenced above: Assayed for LDH activity were 5L of a sample that was diluted 6 to 1. The activity in the reaction vessel, which has a volume of 3 mL, is 0.30 U. What is the A/min observed? What is the relative activity of the original sample? (I calculated a relative activity of 360 U/mL from question 1 with an A/min change of 0.622) Using this information I get the following: 140ug/uL=14ug/uL=14mg/mL x 5 dilutions= 70mg/mL For specific activity= (U/mL)/(mg/mL)=(360 U/mL)/(70mg/mL)= 5.14 U/mg Does this look correct?

Design a buffer that has a pH of 4.86 using one of the weak acid/conjugate base systems shown below. Weak Acid Conjugate Base Ka pKa HC2O4- C2O42- 6.4×10-5 4.19 H2PO4- HPO42- 6.2×10-8 7.21 HCO3- CO32- 4.8×10-11 10.32 How many grams of the potassium salt of the weak acid must be combined with how many grams of the potassium salt of its conjugate base, to produce 1.00 L of a buffer that is 1.00 M in the weak base? grams potassium salt of weak acid = g grams potassium salt of conjugate base = g

A student wishes to determine the chloride ion concentration in a water sample at 25 °C using a galvanic cell constructed with a graphite electrode and a half-cell of AgCl(s) + e⁻ → Ag(s) + Cl⁻(aq) E°red = 0.2223 V And a copper electrode with 0.500 M Cu²⁺ as the second half cell Cu²⁺(aq) + 2 e⁻ → Cu(s) E°red= 0.337 V The measured cell potential when the water sample was placed into the silver side of the cell was 0.0657 V.

What is the standard potential of the cell?

What is the value of standard free energy (in kJ) for this reaction?

What is the balanced equation for the overall reaction in acidic solution?

The measured cell potential is 0.0657, what is the concentration of chloride ions in the solution?

Calculate BOD5 of all 3 samples.

How will you prepare 250 mL of 0.01 M NaOH from NaOH pellets? Please describe in detail how to properly handle, weight, and dissolve the NaOH pellets, and how you would store the solution

Compressibility, τ, is defined as: τ = − 1 /ν *(dν/ dp) Show that the ratio of the isothermal compressibility to the isentropic compressibility is equal to the specific heat ratio for a perfect gas.

If a histidine sidechain in a binding site is protonated in the free protein, but deprotonated in the ligand-bound state, how would pH affect the interaction?

A.) No effect

B.) Lower Kd at lower pH

C.) Higher Kd at lower pH

D.) Only ΔH would change with pH

Consider the diprotic acid h2a with k1=1.00x10-4 and k2=1.00x10-8. find the pH and concentrations of h2a, ha-, and a2- in (a) 0.100 M H2A (b) 0.100 M NaHA (c) 0.100 M Na2A

Le Chatelier's principle states that a chemical system must have a shift in direction in order to force the system to reach equilibrium.

a.true

b.false

Calculate the mass of ammonium chloride required to prepare 25 mL of a 2.0 M solution, and the mass of calcium chloride required to prepare 25 mL of a 2.0 M solution.

A 100 mg vitamin C tablet weighed 1.627 g. A student crushed the tablet and transferred 0.159 g of the crushed powder into a 100 mL volumetric flask, dissolved the powder in ~30 mL DI water, then filled the flask to the calibration line with DI water and mixed well to create Solution 1. The student then transferred 23.2 mL of Solution 1 into a 100 mL volumetric flask and diluted to the calibration line with DI water to create Solution 2. Calculate the expected concentration (in mM) of ascorbic acid in Solution 2.