How much ice (in grams) would have to melt to lower the temperature of 354 mL of water from 26 ∘C to 6 ∘C? (Assume the density of water is 1.0 g/mL.)

Piperazine, HN(C4H8)NH, is a diprotic weak base used as a corrosion inhibitor and an insecticide and has the following properties:

pKb1=4.22 pKb2=8.67

For writing the reactions of this base in water, it can be helpful to abbreviate the formula as Pip:

Pip+H2OPipH++H2O??PipH++OH?PipH22++OH?

The piperazine used commercially is a hexahydrate with the formula C4H10N2?6H2O.

a. Calculate the pH after 2.575mL of HCl have been added.

b. Calculate the pH when 12.875mL of HCl has been added.

c. What is the pH at the first midway point?

please don't copy and paste that yahoo answers bs, it doesn't give the right answer.

The corrosion of rebar inside concrete structures is serious issue for the safety and stability of bridges and buildings. The chemistry of corrosion is complex, but a simplified chemical model (iron rusting) is: 4Fe (s) + 3O2 (g) ⟶ 2Fe2O3 (s) ∆H = −1.65 × 103 kJ a) How much heat is released when 1.00 pound of iron rusts? b) If 6.25 × 104 kJ is released, how many kilograms of iron have rusted?

A photometer with a linear response to radiation gave a reading of 690 mV with a blank in the light path and 101 mV when the blank was replaced by an absorbing solution. Calculate

the transmittance and absorbance of the absorbing solution.

Transmittance =

Absorbance =

the expected transmittance if the concentration of absorber is one half that of the original solution.

Transmittance =

the transmittance to be expected if the light path through the original solution is doubled.

Transmittance =

Identify which sets of quantum numbers are valid for an electron. Each set is ordered (n,?,m?,ms).

Check all that apply.

What is the pH of the solution formed when 30.0 g of potassium nitrite (KNO2) is dissolved in 1.00 L of water.

Examples of chemical equilibrium in Nature or in our daily environment (homogeneous and heterogeneous). Can you find examples with small and large extent?

In gluconeogenesis, pyruvate is converted to PEP in two reactions. These reactions include an initial carboxylation followed by a decarboxylation in the second reaction. Based on these two reactions, you would assume that if radio-labeled 14CO2 was present in the reactions, it would not be incorporated into PEP. However, when 14CO2 is present with rat liver cells 14C slowly begins to appear in PEP and eventually on carbons 3 and 4 of glucose. Diagram a series of reactions that would explain this observation. You need to clearly show the location of the radiolabeled 14C in all reactions and indicate any changes in localization with the cells

This is Organic Chemistry Lab, Solvent Extraction.

1. What are the criteria for solubility of organic molecules in water?

2. If methylene chloride was used as the organic solvent in solvent extraction, instead of ether, what would the top layer be in the separation step?

3. What formula was used to calculate interaction of organic compounds with the stationary phase?

4. In the given mixture (liquid-liquid), which compound (be specific) has the weakest interaction with the stationary phase? Why?

What is the pH of a solution containing 0.383
mol L^-1 CH₃COOH and 0.392 CH₃COO^- mol L^-1 ? Round your answer to 2 decimal places.

Calculate the molar solubility of Ag₂CrO₄(s) in (Solubility Product K_sp at 25 °C is 9.0 × 10⁻¹²)

A) pure water

B) in 0.500 L of a solution containing 0.950 g K₂CrO₄

Hippuric acid (HC9H8NO3), found in horse urine, has pKa=3.62.

Calculate the pH in 0.150 M hippuric acid.

I need to know the procedures of the experiment below :

Separation of a Three-Component Mixture by Extraction ​

benzoic acid     ethyl 4-hydroxybenzoate diphenyl sulfone

A 1.5-gram sample of a 1:1:1 (by weight) mixture of benzoic acid, ethyl 4-hydroxybenzoate and diphenyl sulfone was added to a 125 mL separatory funnel. Isopropyl acetate (20 mL) was added to the separatory funnel and the mixture swirled until all solids had dissolved. The solution was sequentially extracted with saturated aqueous NaHCO3 solution (4 X 5 mL), then with water (1 X 5 mL); with the aqueous extracts from each extraction being added to a 50 mL beaker (beaker 1). [The separatory funnel should be shaken for at least 1 minute during each of the four NaHCO3 extractions. Venting of the funnel should be done every 20-25 seconds during each extraction. When draining off the aqueous layer in these and all subsequent extractions leave a two mm tall layer of aqueous solution in the separatory funnel. This greatly reduces the amount of organic layer that contaminates the aqueous extracts.] Next the organic layer was extracted sequentially with 5% aqueous NaOH solution (3 X 5 mL) then with water (1 X 5 mL). Each aqueous extract was collected in a 50 mL beaker (beaker 2). [The separatory funnel should be shaken for at least 1.0 minute during each NaOH extraction..] The remaining organic layer is extracted with saturated aqueous NaCl solution (5 mL) and the aqueous layer is discarded [Do not leave any water in the funnel after this extraction]. The organic layer is transferred to a 50 mL erlenmeyer flask (flask 3). The separatory funnel is washed with isopropyl acetate (2 X 2 mL) with each washing being added to flask 3. The organic solution in flask 3 is dried (Na2SO4) then decanted into a tared 50 mL Erlenmeyer flask (flask 4). The drying agent is washed with isopropyl acetate (2 X 1 mL) with each rinse being added to flask 4. The solvent in flask 4 is evaporated to give crude diphenyl sulfone as a white solid: .416 g, 83.2%, M. pt.=121-127oC. [Evaporate the solvent using a hot plate sat on a moderate (4) setting. You must be very careful not to overheat the product when all the solvent has boiled away. The only way to actually know when all of the solvent has been removed is to weight the flask at the point of “ presumed dryness”, then reheat for a few seconds and re-weigh the flask. If the weight does not change, the product is solvent free. An alternative, and probably better, procedure is to evaporate the isopropyl acetate until only 3-5 mL of solution remains, cool, add hexane (10 mL), chill in an ice bath then filter. Both procedures work well. If insufficient time remains to isolate this material on day 1, then store the dried isopropyl acetate solution in your drawer until the next lab period. The solvent will have evaporated by then. Optional: tlc (alumina,

70/30 hexane/ethyl acetate) showed a single spot, Rf = .58. The crude product is recrystallized from toluene to give the crude product; M. pt.= 125-127 C.]

The aqueous solution in beaker 1 was acidified (acid to litmus paper) by the addition of 6 M HCl solution to give a white precipitate. [Caution! Foaming will occur due to liberation of CO2] After cooling the resulting mixture in an ice bath for 10 minutes, the solid was isolated by vacuum filtration, washed with ice water (3 X 1ml), and air dried to give crude benzoic acid as a white solid: .358 g, 71.6%, M. pt.= 115-120oC. [OPTIONAL: tlc (alumina, 70/30 hexane/ethyl acetate) showed a single spot (Rf = .03). This material was recrystallized from water to give pure benzoic acid; M. pt. = 118- 120C.]

The aqueous solution in beaker 2 was acidified (acid to litmus paper) by the addition of 6 M HCl to give a white precipitate. The resulting aqueous mixture was cooled in an ice bath for 10 minutes. The resulting white solid was isolated by vacuum filtration, washed with ice water (3 X 1 mL), and air dried to give the crude ethyl 4-hydroxybenzoae: .353 g, 70.6%, M.pt.= 113-117oC. [Optional: tlc (alumina, 70/30 hexane/ethyl acetate) showed a single spot (Rf = .42). The crude material was recrystallized from 1/1 toluene/hexane to give the pure ethyl 4-hydroxybenzoate as a white solid; M. pt.= 115- 117C.]