Chemistry M.C.Q (1 Marks)

1. The chemical used in process of tanning is known as Tannin.
2. It contains negatively charged colloidal particles whereas leather contains positively charged colloidal particles.
3. When the leather is soaked in tannin, due to the difference in charges, mutual coagulation occurs.
4. This coagulation results in the hardening of the leather after tanning process.

A catalyst is a substance, which increases the rate of reaction without itself being consumed at the end of the reaction, and the phenomenon is called catalysis. There are some catalysts which decrease the rate of reaction and such catalysts are called negative catalyst. Obviously, the catalyst accelerating the rate will be positive catalyst. However, the term positive is seldom used and catalyst itself implies positive catalyst. Catalysts are generally foreign substances but sometimes one of the product formed may act as a catalyst and such a catalyst is called "auto catalyst" and the phenomenon is called auto catalysis.

Potassium salts of fatty acids, containing no free alkali, are called soft soaps.

Sol is a colloidal suspension when a solid is dispersed in a liquid.
An example of sol is a gel, blood, paint, etc.
A liquid is dispersed in a gas called aerosols.
A gas dispersed in liquid or solid called foam.

High temperature is not favourable for physical adsorption since it is an exothermic process.

Peptisation is the process of converting freshly prepared precipitate into colloid.

The emulsifying agent used in oil in water emulsion is protein. Milk is an example of oil in water emulsion. It consists of liquid fat dispersed in water. Milk proteins act as an emulsifying agent.

An emulsion is a colloid of two or more immiscible liquids where one liquid contains a dispersion of the other liquids. In other words, an emulsion is a special type of mixture made by combining two liquids that normally don't mix.
Oil and water mixtures are emulsions when shaken together. The oil will form drops and disperse throughout the water.

The contact process is the current method of producing sulfuric acid in the high concentrations needed for industrial processes. Platinum used to be the catalyst for this reaction. However, as it is susceptible to reacting.

A catalyst is a substance, which increases the rate of reaction without itself being consumed at the end of the reaction, and the phenomenon is called catalysis. There are some catalysts which decrease the rate of reaction and such catalysts are called negative catalyst. Obviously, the catalyst accelerating the rate will be positive catalyst. However, the term positive is seldom used and catalyst itself implies positive catalyst. Enzymes acts as catalyst for biological process and lower activation energy and it increases efficiency.

The process of formation or conversion of a precipitate into a colloidal solution is called peptisation.

Stabilizers are the substance that are added in lyophobic sols to increase their stability.
Examples of stabilizers are an ammonium salt and a citrate.

When the force of attraction existing between adsorbate and adsorbent are weak Vanderwaal forces of attraction, the process is called Physical Adsorption or Physisorption. When the force of attraction existing between adsorbate and adsorbent are chemical forces of attraction or chemical bond, the process is called Chemical Adsorption.

The charge on the sol particles is due to one or more reasons, Viz.,

1. Due to electron capture by sol particles during electro dispersion of metals.
2. Due to preferential adsorption of ions from solution and/or.
3. Due to formulation of electrical double layer.

Peptization is a process of passing of a precipitate into colloidal particles on adding suitable electrolyte. The electrolyte added is known as peptizing agent.
For example: A reddish brown colored colloidal solution is obtained by adding small quantity of ferric chloride solution to the freshly precipitated ferric hydroxide.

The rate of physisorption is inversely proportional to temperature. The rate of physisorption increases with the decrease in temperature as it is an exothermic process.

Physisorption is not specific to any gas since it involves van der Waals forces and no specific bonds are formed.

Peptization is the process responsible for the formation of stable dispersion of colloidal particles in dispersion medium. In other words it may be defined as a process of converting a precipitate into colloidal sol by shaking it with dispersion medium in the presence of small amount of electrolyte. The electrolyte used in this process is called as peptizing agent.

Platinum and Palladium adsorb hydrogen on its surface.Platinum and Palladium are nobel/ inert metals they do not react with hydrogen.

A molecule of soap has two dissimilar ends. At one end is the hydrocarbon chain, which is water repellent and the other end is carboxylate anion which is polar end.
When soap is dissolved in water, many molecules come together and from a group called micelle. These micelles are formed because their hydrocarbon chains come together and the polar ends are projected outward.
When a Cloth with a spot of oil is soaked into a soap solution, soap dissolves tiny oil droplets by the hydrophobic end in the middle of the micelle. Due to the outer polar ends, these micelles dissolve in water and are washed away. In this way cloth gets cleaned.

Substances, which are added to soaps change their properties in order to make them more useful for a particular application, are called fillers. Fillers make the soap harder, harsher on the skin and lower the cost.

The enthalpy change value of the reaction will not be affected by a catalyst. A catalyst will only lower the required activation energy for the reactions. Since it will lower the activation energy for both the forward and reverse reactions to the same extent, the net change in enthalpy is zero.