A 0.450 gram sample of impure CaCO3 (s) is dissolved in 50.0 mL of 0.150 M HCl (aq). The equation for the reaction is CaCO3(s) + 2HCl --> CaCL2 (aq) + H2O (l) + CO2 (g). The excess HCl (aq) is titrated by 7.20 mL of 0.125 M NaOH (aq). Calculate the mass percentage of CaCO3 (s) in the sample.

1. Graduated cylinders are not as precisely calibrated as are burets or volumetric pipets. Briefly explain why it is acceptable to measure the KI and HCI solutions used in the titration with graduated cylinders rather than with pipets or burets. 2. Would the following procedural errors result in an incorrectly high or low calculated precent NaOCI in commercial bleaching solution? Briefly explain. (1) A student failed to allow the volumetric pipet to drain completely when transferring the diluted bleaching solution to the Erlenmeyer flask. (2) A student blew the last drops of solution from the pipet into the volumetric flask when transfeering commercial bleaching solution to the flask. (3) A student began a titration with an air bubble in the buret tip. Thhe bubbl came out of the tip after 5 mL of Na2S2O3 solution had been released.

Why is Vmax not a constant? Why do we want to analyze kcat instead of Vmax?

A. While both NaBH4 and LiAlH4 can both be used to reduce ketones and aldehydes, the procedure that you followed in lab would not result in the fluorenol product if NaBH4 were simply replaced with LiAlH4.

i) Explain why.

ii) What change to the procedure would have to be made to use LiAlH4 tosuccessfully reduce fluorenone to fluorenol?

B. NaBH4 is not capable of reducing esters since estersare less reactive than ketones. Explain structurally why this is the case.

C. In a lab, NaBH4 is kept in a dessicator to avoid prolonged contact with water in the atmosphere. This is done since waterwill react with NaBH4. Write the balanced equation for the decomposition of NaBH4 by water.

D. It is found that a bottle of NaBH4 in a lab contains 70% NaBH4 by mass as a significant portion has reacted with atmospheric water as described in question 3 above. What is the minimum that a student should weigh out to fully reduce 3.18 g of fluorenone?

Write the complete redox and the two half-reactions for the reaction of aluminum and copper. Which species is oxidizing agent? The reducing agent? How many electrons were transferred?

A compound containing xenon and fluorine, Xex,Fy, was produced by shining bright sunlight on a gaseous mixture of 0.439 g of Xe and excess fluorine. If all the xenon reacts, and 0.693 grams of the compound are formed, what is the empirical formula of the compound?

A 0.158 gram sample of a salt, comprised of barium and one of the halide ions, was dissolved in water, and an excess of sulfuric acid was added to form barium sulfate, BaSO4. After filtering and drying, the solid BaSO4 weighed 0.124 grams. Determine the identity of the halide and the formula of the barium halide.

At 2300 K the value of K of the following reaction is 1.5 x 10^-3:

N₂(g) + O₂(g) ↔ 2NO(g)

At the instant when a reaction vessel at 2300K contains 0.50M N₂, 0.25M O₂, and 0.0042M NO, by calculation of the reaction quotient (Q), is the reaction mixture at equilibrium? If not, in which direction will the reaction proceed to reach equilibrium?

The value of Kc for the reaction:

N₂O₄(g) ↔ 2NO₂ (g)

is 0.21 at 373K. If a reaction vessel at that temperature initially contains 0.030M NO₂ and 0.030M N₂O₄, what are the concentrations of the two gases at equilibrium? First, the reaction quotient (Q) [page 645 of textbook] must be calculated, and then use the I.C.E table [page 648-650 of the textbook] to determine the equilibrium concentrations.

Assuming 100% yield, how much hexynyl lithium is produced from the reaction that you performed in the lab of LiMDS with 1-hexyne (0.22 mL)? Using 1 mL of 1.0 M lithium bis(trimethylsilyl)amide solution in THF and 0.22 mL of 1-hexyne. (1‐hexyne density = 0.71 g/mL).Show all work .

what is pH of 15.0g KH2PO4 + 27.0 g Na2HPO4 dissolved in H2O plus enough H2O to fill to 1L

Subtract/Multiply/Divide using Significant figures

1.

(16.75 - 6.2) x (9.56 x 10^-19)

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(6.75^3.2) x (8.5679 x 10¹¹)

This is just one problem, just dividing it

2. Convert 9.64 x 10¹⁴ pm³ to nanometers

Calculate the pH of a solution formed by mixing 65 mL of 0.16 M NaHCO3 with 75 mL of 0.29 M Na2CO3. Express your answer using two decimal places.

Co(II) was used as an internal standard to analyze a sample of Ti(IV) with atomic absorption spectroscopy (AAS). A standard mixture containing 1.40 μg Co/mL and 1.35 μg Ti/mL measured by AAS produced a signal-to-signal ratio of 2.41 Ti: 1.00 Co. A mixture was prepared by combining 4.50 mL of a Ti(IV) solution of unknown concentration with 4.00 mL of a 14.1 μg/mL solution of Co(II). The absorbance of the mixture at the Ti(IV) wavelength was 0.175 and the absorbance at the Co(II) wavelength was 0.187. Determine the concentration, in moles per liter, of Ti(IV) in the original unknown solution.

Calculate the pH of a mixture that contains 0.13 M of HNO3 and 0.20 M of HC6H5O.

Explain the purpose of the components of an acrylamide gel.