General Chemistry Answers

Consider the titration of 50.00 mL of a mixture of NaI and NaBr with 0.0500 M silver nitrate. The first equivalence point was observed at 10.50 mL and the second at 25.50 mL. Calculate the molar concentration of the two salts in the sample

The concentration of sulfate in a solution containing a mixture of sulfuric acid is to be determined. A 25.0 mL portion of the sample is treated with 10.00 mL of 0.0500 M BaCl₂. The resulting precipitate is filtered off and the supernatant solution containing the Ba²⁺ is then titrated with 0.0354 M EDTA which gives an end point at 7.45 mL.

(a) Identify the type of EDTA titration method used.

(b) Calculate the molar concentration of sulfate in the sample.

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A 20.0 mL portion of a deep well water sample was diluted to 250.00 mL solution. A 50.0 mL aliquot of this diluted sample water was buffered at pH 10 and required 8.50 mL of a standard EDTA. The titrant was standardized using 100.0 mL containing 0.8622 mg primary standard calcium carbonate, CaCO₃ (FW=100.09 g/mol) which required 15.45 mL for titration.

(a) Identify a possible indicator and its endpoint color.

(b) Calculate the molarity of the EDTA solution.

(c) Calculate the total hardness of the water as ppm CaCO₃.

(d) Identify the quality of the water sample in terms of hardness.

The Sn in a 0.4352 g mineral specimen was reduced to the +2 state and titrated with 29.77 mL of 0.01735 M K2Cr2O7. Identify:

(a) balanced redox reaction

(b) oxidizing agent

(c) reducing agent

(d) type of redox titrimetry used

(e) appropriate indicator and its type

(f) color at the end point

(g) weight percent Sn (118.71 g/mol) in the sample

A 10.0 mL sample containing Fe³⁺ and Cu²⁺ was diluted to 100.0 mL solution. A 20.0 ml aliquot required 25.0 ml of 0.0500 M EDTA for complete titration. A separate 20.0 ml aliquot of the diluted sample was treated with NH₄F to protect the Fe³⁺. Then the Cu²⁺ was treated with thiourea. Upon addition of 25.0 mL of 0.0500 M EDTA, the Fe³⁺ was liberated from its fluoride complex and formed an EDTA complex. The excess EDTA required 21.5 mL of 0.0180 M Pb²⁺ to reach an end point, using xylenol orange.

When a 1.0g sample of copper (II) sulphate pentahydrate was heated so that the waters of hydration were driven off, the mass of the anhydrous salt remaining was found to be 0.6390g. What is the experimental value of the percent water of hydration? Give the formula for the sample above and also the heating process from the hydrated form to the anhydrous form

Write 50 word describing Henderson-Hasselbalch in chemistry. 

Cite 2 instances that will make a buffer effective.

S

o

(J/mol•K) 240 69.91 146 210.7

CH

3OH, is 35.20 kJ/mol. Its boiling

point is 64.6°C