List of top Chemistry Questions

A reaction is first order in A and second order in B.

  1. Write the differential rate equation. 
  2. How is the rate affected on increasing the concentration of B three times? 
  3. How is the rate affected when the concentrations of both A and B are doubled?
At 300 K, 36 g of glucose present in a litre of its solution has an osmotic pressure of 4.98 bar. If the osmotic pressure of the solution is 1.52 bars at the same temperature, what would be its concentration?

Give IUPAC names of the following ethers:

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 epression constant for benzene is \(5.1 K\, kg mol^{–1}\). Calculate atomic masses of A and B.

Give a reason for the higher boiling point of ethanol in comparison to methoxymethane.

A \(5\%\) solution (by mass) of cane sugar in water has freezing point of 271K.Calculate the freezing point of \(5\%\) glucose in water if freezing point of pure water is 273.15 K.

How are the following conversions carried out?

(i)Propene\(\rightarrow\)Propan-2-ol.

(ii)Benzyl chloride\(\rightarrow\)Benzyl alcohol.

(iii)Ethyl magnesium chloride\(\rightarrow\)Propan-1-ol.

(iv)Methyl magnesium bromide\(\rightarrow\)2-Methylpropan-2-ol.

Calculate the mass of a non-volatile solute (molar mass \(40 g mol^{–1}\)) which should be dissolved in 114 g octane to reduce its vapour pressure to \(80\%\)

What is the effect of temperature on the rate constant of a reaction? How can this temperature effect on rate constant be represented quantitatively?

How will you prepare the following compounds from benzene?You may use any inorganic reagent and any organic reagent having not more than one carbon atom
(i)Methyl benzoate 
(ii) m-Nitrobenzoic acid 
(iii)p-Nitrobenzoic acid 
(iv)Phenylacetic acid 
(v)p-Nitrobenzaldehyde.

Mention the factors that affect the rate of a chemical reaction.

The decomposition of dimethyl ether leads to the formation of CH4, H2 and CO and the reaction rate is given by 
\(Rate = k [CH_3OCH_3]^{\frac 32}\)
The rate of reaction is followed by increase in pressure in a closed vessel, so the rate can also be expressed in terms of the partial pressure of dimethyl ether, i.e., 
\(Rate = k(p_{CH_3OCH_3})^{\frac 32}\)
If the pressure is measured in bar and time in minutes, then what are the units of rate and rate constants?

The decomposition of NH3 on platinum surface is zero order reaction. What are the rates of production of N2 and H2 if k = 2.5 x 10-4 mol-1Ls-1?

Give simple chemical tests to distinguish between the following pairs of compounds.
(i)Propanal and Propanone 
(ii)Acetophenone and Benzophenone
(iii)Phenol and Benzoic acid
(iv)Benzoic acid and Ethyl benzoate
(v)Pentan-2-one and Pentan-3-one 
(vi)Benzaldehyde and Acetophenone
(vii)Ethanal and Propanal
 

For the reaction:
\(2A + B → A_2B\)
the rate = k[A][B]2 with k= 2.0 x 10-6 mol-2L2s-1. Calculate the initial rate of the reaction when [A] = 0.1 mol L-1, [B] = 0.2 mol L-1. Calculate the rate of reaction after [A] is reduced to 0.06 mol L-1.

From the rate expression for the following reactions, determine their order of reaction and the dimensions of the rate constants.

  1. 3NO(g) \(\to\) N2O (g) Rate = k[NO]2
  2. H2O2 (aq) + 3I−(aq) + 2H+ \(\to\) 2H2O(l) + I3-  Rate = k[H2O2][I−]
  3. CH3CHO(g) \(\to\) CH4(g) + CO(g)  Rate = k [CH3CHO]\(\frac 32\)
  4. C2H5Cl(g) \(\to\) C2H4(g) + HCl(g)  Rate = k [C2H5Cl]

Arrange the following compounds in increasing order of their property as indicated:\((i)Acetaldehyde,Acetone,\)\(Di-tert-butyl ketone,Methyl tert-butyl ketone\)(reactivity towards \(HCN\))\((ii) CH_3CH_2CH(Br)COOH,CH_3CH(Br)CH_2COOH,\)\((CH_3)_2CHCOOH,CH_3CH_2CH_2COOH\)(acid strength)\((iii)Benzoic\space acid,4-Nitrobenzoic \space acid\),\(3,4-Dinitrobenzoic \space acid,4-Methoxybenzoic \space acid\)(acid strength).
 

An organic compound(A)(molecular formula\( C_8H_{16}O_2\))was hydrolysed with dilute sulphuric acid to give a carboxylic acid(B)and an alcohol(C).Oxidation of(C)with chromic acid produced (B).(C)on dehydration gives \(but-1-ene\).Write equations for the reactions involved.
 

Write structural formulas and names of four possible aldol condensation products from propanal and butanal.In each case,indicate which aldehyde acts as nucleophile and which as electrophile.
 

How will you convert ethanal into the following compounds?
(i) Butane-1, 3-diol
(ii) But-2-enal
(iii) But-2-enoic acid

Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic configuration and coordination number. Also give stereochemistry and magnetic moment of the complex:
\((i) K[Cr(H_2O)_2(C_2O_4)_2].3H_2O\)
\((ii)[Co(NH_3)_5Cl]Cl_2\)
\((iii) CrCl_3(py)_3\)
\((iv) Cs[FeCl_4]\)
\((v)K_4[Mn(CN)_6]\)

Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory: 
\((i) [Fe(CN)_6]^{4-} \)
\((ii) [FeF_6]^{3-}\)
\((iii) [Co(C_2O_4)_3]^{3-} \)
\((iv) [CoF_6]^{3-}\)
The vapour pressure of water is 12.3 kPa at 300 K. Calculate vapour pressure of 1 molal solution of a non-volatile solute in it
Heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components are 105.2 kPa and 46.8 kPa respectively. What will be the vapour pressure of a mixture of 26.0 g of heptane and 35 g of octane?

Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents. 
(i)\(PhMgBr\) and then \(H3O + \)
(ii)Tollens' reagent 
(iii) Semicarbazide and weak acid 
(iv)Excess ethanol and acid 
(v) Zinc amalgam and dilute hydrochloric acid