Recent questions tagged sec-c

Calculate the depression in the freezing point of water when 10 g of $CH_3CH_2CHClCOOH$ is added to 250 g of water. $K_a = 1.4 \times 10^{–3}, K_f = 1.86 K kg mol^{–1}$.

asked Aug 5, 2014 by sreemathi.v

1 answer

Nalorphene $(C_{19}H_{21}NO_3)$, similar to morphine, is used to combat withdrawal symptoms in narcotic users. Dose of nalorphene generally given is 1.5 mg. Calculate the mass of $1.5 \times 10^{–3} m$ aqueous solution required for the above dose.

asked Aug 5, 2014 by sreemathi.v

1 answer

Two elements A and B form compounds having formula $AB_2$ and $AB_4$. When dissolved in 20 g of benzene ($C_6H_6$), 1 g of $AB_2$ lowers the freezing point by 2.3 K whereas 1.0 g of $AB_4$ lowers it by 1.3 K. The molar depression constant for benzene is 5.1 K $kg mol^{–1}$. Calculate atomic masses of A and B.

asked Aug 5, 2014 by sreemathi.v

1 answer

A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate: vapour pressure of water at 298 K.

asked Aug 5, 2014 by sreemathi.v

1 answer

A solution containing 30 g of non-volatile solute exactly in 90 g of water has a vapour pressure of 2.8 kPa at 298 K. Further, 18 g of water is then added to the solution and the new vapour pressure becomes 2.9 kPa at 298 K. Calculate: molar mass of the solute

asked Aug 5, 2014 by sreemathi.v

1 answer

What is meant by positive and negative deviations from Raoult's law and how is the sign of $\Delta_{mix}H$ related to positive and negative deviations from Raoult's law?

asked Aug 5, 2014 by sreemathi.v

1 answer

How many mL of 0.1 M HCl are required to react completely with 1 g mixture of $Na_2CO_3$ and $NaHCO_3$ containing equimolar amounts of both?

asked Aug 4, 2014 by sreemathi.v

1 answer

A solution of glucose in water is labelled as 10% w/w, what would be the molality and mole fraction of each component in the solution? If the density of solution is $1.2 g mL^{–1}$, then what shall be the molarity of the solution?

asked Aug 4, 2014 by sreemathi.v

1 answer

An element has a body centred cubic structure with a cell edge of 288 pm.The density of the element is $7.2gcm^{-3}$.calculate the number of atoms present in 280g of the element.

asked Aug 4, 2014 by sreemathi.v

1 answer

You are given marbles of diameter 10mm.They are to be placed such their centres are lying in a square bond by four lines each of length 40mm.What will be the arrangement of marbles in a plane so that maximum number of marbles can be placed inside the area?Derive the expression for the number of molecules per unit area.

asked Aug 1, 2014 by sreemathi.v

1 answer

In a crystalline solid,having formula $AB_2O_4$,oxide ions are arranged in cubic close packed lattice while cations A are present in tetrahedral voids and cations B are present in octahedral voids.What percentage of the tetrahedral voids is occupied by A and B?

asked Aug 1, 2014 by sreemathi.v

1 answer

Prove that the void space percentage in zinc blende structure is 25%

asked Aug 1, 2014 by sreemathi.v

1 answer

KCl crystallizes in the same type of lattice as does $NaCl$.Given that,$\large\frac{r_{Na^+}}{r_{Cl^-}}=$$0.5,\large\frac{r_{Na^+}}{r_{K^+}}=$$0.7$.Calculate the ratio of the side of the unit cell for KCl to that for NaCl and the ratio of density of NaCl to that for KCl.

asked Aug 1, 2014 by sreemathi.v

1 answer

Explain the following with suitable examples: 12-16 and 13-15 group compounds.

asked Jul 31, 2014 by sreemathi.v

1 answer

Explain the following with suitable examples: Antiferromagnetism

asked Jul 31, 2014 by sreemathi.v

1 answer

Explain the following with suitable examples: Ferrimagnetism

asked Jul 31, 2014 by sreemathi.v

1 answer

Explain the following with suitable examples: Paramagnetism

asked Jul 31, 2014 by sreemathi.v

1 answer