Zn is to be recovered from an ore containing ZnS. The ore is first roasted with oxygen to produce ZnO, which is leached with aqueous H2SO4 to produce water - soluble ZnSO4 and an insoluble, worthless residue called gangue. The decanted sludge of 20,000 kg/h contains 5 wt% water, 10 wt% ZnSO4, and balance as gangue. This sludge is to be washed with water in a continuous, countercurrent washing system to produce an extract, called a strong solution, of 10 wt% ZnSO4 in water, with a 98% recovery of ZnSO4. Assume that underflow from each washing stage contains, by weight, two parts of water (sulfate - free basis) per part of gangue. Determine the stages required.
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Calculate the percent composition and determine the molecular formula and the empirical formula for the nitrogen-oxygen compound that results when 12.04 g of nitrogen is reacted with enough oxygen to produce 39.54 g of product. The molar mass of the product is 92.02 g. Proper significant figures when needed.
Percent Oxygen:
Percent Nitrogen:
Empirical Formula:
Molecular Formula:
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A photocell, such as that illustrated in Figure 6.7(b), is a
device used to measure the intensity of light. In a certain
experiment, when light of wavelength 560 nm is directed on to the
photocell, electrons are emitted at the rate of 9.6 ✕
10-13 C/s. Assume that each photon that impinges on the
photocell emits one electron.
How many photons per second are striking the photocell?
photons/s
How much energy per second is the photocell absorbing?J/s
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10.4g of Mercury(2) oxide will produce what volume of oxygen in the reaction where mercury(1) oxide and oxygen produces mercury(2) oxide
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12.You have a mixture of solids in the ratio of 50:3 for A : B. You are planning to use the technique of recrystallization to purify A and realize that you will first need to determine which solvent or solvent pair would be appropriate. Describe the solubility properties of the solvent that you would want to use, briefly explaining your rationale.
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An acidic buffer solution can be prepared from phosphoric acid and dihydrogen phosphate.
a. What is the pH of solution prepared by mixing 23.5g of NaH 2 PO 4 and 15.0mL of concentrated phosphoric acid (14.7M) in enough water to give 1.25L of solution?
b. By how much does the pH of this buffer solution change on the addition of 3.50 mL of 6.0M HCl?
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using three enzymatic steps propose a pathway for the conversion of alpha ketoglutartate to 2-oxoadipate. Draw the missing intermediates and indicate the chemistry involved in each reaction. Include any cofactors that might be required.
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You have 1 M solutions of H3PO4, NaH2PO4, Na2HPO4, Na3PO4 (no NaOH).
=> Using only two of these solutions, how would you prepare 150 mL of 1 M phosphate buffer at pH 3.0?
| A) |
131.4 mL of NaH2PO4 + 18.6 mL H3PO4 |
|
| B) |
50 mL Na2HPO4 + 100 mL Na3PO4 |
|
| C) |
75 mL Na2HPO4 + 75 mL Na3PO4 |
|
| D) |
18.6 mL of NaH2PO4 + 131.4 mL H3PO4 |
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The combustion of liquid ethanol (c2H5OH) produces Carbon Dioxide and water. After 4.62 mL of ethanol ( density= 0.789 g/mL) was allowed to burn in the presence of 15.55 g of Oxygen gas, 3.72 mL of water (density=1.00 g/mL) was collected. Determine the limiting reactant, theoretical yield of H20, and percent yield for the reaction. (hint: write a balanced equation for the combustion for the combustion of ethanol.)
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. A water solution has 1.00x10-2 moles of H+ in 10.00 liters A. What is the [H+] in the solution? B. What is the pH ? C. What is the [OH-] ions? D. Is the solution acidic or basic ? E. What is the pH if water is added to make the volume 100.0 liters?
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An element crystallizes in a body-centered cubic lattice. The edge of the unit cell is 3.28 Å in length, and the density of the crystal is 6.50 g/cm3 .
a.) Calculate the atomic weight of the element.
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Balance each of the following reations using the half reaction method. Show all work
a. Bi(OH)3(S) + Sn(OH)3-(aq) ---> Sn(OH)62- (aq) + Bi(s) (Basic solution)
b. BrO3-(aq) + Sb3+(aq) ---> Br - (aq) + Sb5+ (aq) (acidic solution)
Thank you for your help!
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1) Zinc reacts with hydrochloric acid according to the reaction equation.How many milliliters of 4.00 M HCl(aq) are required to react with 5.85 g of an ore containing 44.0% Zn(s) by mass?
2) The amount of I3–(aq) in a solution can be determined by titration with a solution containing a known concentration of S2O32–(aq) (thiosulfate ion). The determination is based on the net ionic equation.
2SO2O3(2-)(aq) +I3(-)(aq) --->>> S4O6(2-)(aq) + 3I(-)(aq)
Given that it requires 25.6 mL of 0.460 M Na2S2O3(aq) to titrate a 10.0-mL sample of I3–(aq), calculate the molarity of I3–(aq) in the solution.
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