dissolving common salt in water is a physical change or chemical change

Scientists theorize that the earth began as a waterless mass of rock surrounded by a cloud of gas. Radioactive materials in the rock and increasing pressure in the earth's interior gradually produced enough heat to melt the interior of the earth. The heavy materials such as iron, then sank. The lig..

Calorimetry - Calorimetry is the measurement of the amount of heat evolved or absorbed in a chemical reaction, change of state, or formation of a solution. We know that heat flows from a hot substance to a cold substance. In Calorimetry, a hot substance and a cold substance are ..

Nuclear energy is released when very small particles of matter split or combine. After the split or combination, they result in small particles or heavy particle. The rest of the mass is changed into energy. This process of changing mass into energy produces the energy. Energy..

When common salt is added to crushed ice to make a freezing mixture the temperature is lowered below 0 o C. This is because ice absorbs heat from salt which is at a higher temperature and some ice melts dissolving some salt in it. This pr..

Introduction - We heat raw food to soften it. We freeze water into ice by cooling it in refrigerator. When we boil water in a kettle we observe the steam oozing from the mouth of the kettle. When the cork is difficult to remove, we slightly heat the mouth of the bottle, so that ..

. It has changed into an atom of another substance which may be unstable (will undergo further disintegration) or stable (will not emit any more particles), it is not possible to control this change. Neither is it possible to reverse it. Changing the temperature, ..

Electrolytes are substances that conduct electricity due to the drifting of ions. The positive ions are called cations, and the negative ions anions. The common examples of electrolytes are aqueous solutions of inorganic salts, acids and bases. Salts like NaCl, KCl are..

Introduction - In the previous chapter we have seen how light gets reflected when it is incident on a surface. Now let us see what happens when a ray of light traveling from one medium to another medium of different density. It is a matter of common experience that a swimming pool appears..

Electroplating of objects by nickel, silver and gold is very common. The conducting material to be electroplated is made the cathode of an electrolytic cell. A strip of metal whose coating is required on the cathode material is used as the anode, while a soluble salt of the sam..

If a current I flows through a potential drop V, the energy lost per second by the drifting charges is VI. In a resistor of resistance R, the loss of energy appears as heat. The rate of heat production P is P = VI = I 2 R = V 2 /R and is independent of the direction of current..