Assignment (Some Basic Concept of Chemistry) - 4 PDF

 

 

Some Basic Concept of Chemistry (Assignment – 4) 1.

(a) What is the molar concentration of a solution containing 16.0 g CH3OH in 200 cm3  solution? (b) The concentration of glucose (C6H12O6) in normal blood is approximately 90 mg per 100 mL. What is the molarity mo larity of the glucose?

2.

(i) How much MH4Cl is required to prepare 100 mL of a solution containing 70 mg NH4Cl  per mL? (ii) Determine the molar concentration of each of the following solutions : (a) 166 g KI per L solution (b) 33.0 g (NH4)2SO4 in 200 mL solution (c) 12.5 g CuSO4.5H2O in 100 mL solution (d) 10.0 mg Al3+ per mL solution

3.

(a) A litre of milk weighs 1.032 kg. k g. The butterfat it contains to the extent ex tent of 4.0% by volume has a density of 865 kg/m3. What is the density of the fat-free “skimmed” milk? 3

(b) Ammonia gas is passed into water, yielding a solution of density 3 of 0.93 g/cm  and containing 18.6% NH 3 by weight. What is the mass of NH3 per cm  of solution? 4.

(a) How many mL of water must be added to 200 mL of 0.65 M HCl to dilute the solution to 0.20 M? (b) What concentration of NaCl finally results from the mixing of 2.00 L of 4.00 M NaCl with 3.00 L of 1.50 M NaCl plus sufficient water to dilute the solution to 10.0 L? (c) What is the volume of the solution that would result by diluting 70.00 70. 00 mL of 0.0913 M  NaOH to a concentration of 0.0150 M?

5.

(a) How would one prepare exactly 3.00 L of 1.00 M NaOH by mixing portions of stock solution of 2.50 M NaOH and 0.400 M NaOH? 3

(b) What150 volume of30.0% 95.0%alcohol alcoholby byweight weight(density (density0.957 0.809g/cm g/cm3)) must be used to  prepare cm3 of 6.

Determine the molar concentration of each ionic species in solution after each of the following operations: (a) 200 mL of 2.0 M NaCl is diluted to 500 mL. (b) 200 mL of 2.0 M BaCl2 is diluted to 500 mL. (c) 200 mL of 3.00 M NaCl is added to 300 mL of 4.0 M NaCl. (d) 200 mL of 2.00 M BaCl2 is added to 400 mL of 3.0 M BaCl2 and 400 mL of water. (e) 300 mL of 3.0 M NaCl is added to 200 mL of 4.0 M BaCl 2.

 

  7.

(a) A mother cell disintegrates into sixty identical cells and each daughter cell further disintegrates into 24 smaller cells. The smallest cells are uniform cylindrical in shape with diameter of 120 Å and each cell is 6000 Å long. Determine molar mass of the mother cell if density of smallest cells is 1.12 g/cm 3? (b) A porous catalyst for chemical reaction has an internal surface area of 800 m2 per cubic centimeter of bulk material. Fifty percent of the bulk b ulk volume consists of the pores (holes), while the other 50% of the volume is made up of the solid substance. Assume that the  pores are all cylindrical tubules of uniform diameter d and length l , and that the measured internal surface area is the total area of the curved surfaces of the tubules. What is the diameter of the each pore.

8.

To a sample of an element X (at. wt. 70) element Y (at. wt. 120) is added as impurity. The ratio atoms of X to Y in the mixture is 1 : 10 -7. How many gms of Y will be required for 100 gm of X for this ratio.

9.

(a) If pure Mohr’s salt [(NH4)2Fe(SO4)2.6H2O] crystals contain 15% iron and 30% water. How much Fe and how much water should be taken to get 20 gm of its crystals. (b) A clay was partially dried and then contained 50% silica and 7% water. The original clay contained 12% water. What is the % of silica in the original o riginal sample?

10.

(a) w1 gm of hydrated blue copper sulphate (CuSO 4.5H2O) crystals are mixed with w2 gm of water. If the density of the crystal (hydrated) is d1 gm/ml, then calculate the molarity & molality of Cu2+, SO42- ions, if resultant solution has density d2 gm/ml. Also calculate the volume change. (b) A mixture of CuSO4.5H2O and MgSO4.7H2O was heated until all the water w ater was drivenoff. If 5.0 g of mixture gave 3 g of anhydrous salts, what was the percentage by mass of CuSO4.5H2O in the original mixture?

11.

The mole fraction of a given sample of I2 in C6H6 is 0.2. The molality I 2 in C6H6 is (a) 0.32 (b) 3.2 (c) 0.032 (d) 0.48

12.

What volume of 0.4 M FeCl3.6H2O will contain 600 mg of Fe 3+? (a) 49.85 mL (b) 26.78 mL (c) 147.55 mL

13.

(d) 87.65 mL

A sample of H2SO4 (density 1.8 g/ml) is 90% by weight. What is the volume of the acid a cid that has to be used to make 1 litre of 0.2 M H2SO4? (a) 16 mL (b) 10 mL (c) 12 mL (d) 18 mL

 

  14.

The mineral quartz (SiO2) and zircon (ZrSiO4) has a density of 2.65 g/cm3 and 4.5 gm/cm3  respectively. A rock composed of quartz and zircon has a density of 3 gm/cm 3% by volume and % by mass of quartz in the sample are (a) 81.1% by vol, 71.7% by mass (b) 61.2% by vol, 55.3% by mass (c) 75% by vol, 60% by mass (d) data insufficient

15.

The molarity of Cl –  in an aqueous solution which was 2% NaCl, 4% CaCl2 and 6% NH4Cl (w/v) will be (a) 0.342 (b) 0.721 (c) 1.12 (d) 2.18

 

 

Some Basic Concept of Chemistry (Assignment – 4)

Answer Key 1. 

(c) 83.33 mL 

(b) 5 × 10-3 M,

(a) 2.5 M,

(i) 7g, (ii) (a) 1 M, (b) 1.25 M, (c) 0.5 M, (d) 0.37 M (a) 1039 kg/m3, (b) 0.173 g/ml (a) 450 mL, (b) 1.25 M, (c) 426 ml (a) 2.14 L of 0.4 M solution, (b) 56.03 mL + (a) 0.8 M Na , 0.8 M Cl , (b) 0.8 M Ba2+, 1.6 M Cl-, (c) 3.6 M Na+, 3.6 M Cl-  (d) 1.6 M Ba2+, 3.2 M Cl-, (e) 1.8 M Na+, 1.6 M Ba2+, 5 M Cl-  7.  (a) 6.6 × 1010 amu, (b) 25 Å   1.714 × 10-5 gm  8.  9.  (a) Fe = 3 gm; H2O = 6 gm, (b) 47.31%  w 4w  d 4w (w  w )  10.  (a) (b) 73.4% ml , (w  w ) ; ((w w  0.36  w )  d  w  d  2. 3.  4.  5.  6. 

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(b) (b) (c) (a) (d)

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