For example, if you are painting your car, it is not a chemical change rather it is a physical change. Colour change of a substance is not always considered a chemical change. It may happen that a chemical reaction is not occurring. However, these are not precise indicators. is seen, it is said that a chemical reaction is taking place. Note: When two or more than two reactants are blended, and change in colour, temperature, etc. Noticeable odour or smell (after the beginning of reaction) Following are the signs of chemical changes: When bonds get broken, and new substances are formed. A chemical change refers to a change in the composition of a substance. Honey and magma have much higher viscosities as compared to water.Ĭhemical changes are quite different. Thick substances have high viscosity than substances which are deemed ‘thin’. Another way to think about viscosity is in regards to thickness. Viscosity refers to the deformation resistance of a specific chemical substance when force is exerted on it. The density of water is 1 g/cm3, so any object that has density lesser than 1 g/cm3 will float and the objects having density more than 1 g/cm3 will sink in water. Moreover, the density of an object is the factor which determines whether it will float or sink in any chemical fluid. The metal baseball is much heavier in its same volume amount. Now, compare this with a paper made baseball. For instance, a metal ball whose size is similar to that of a baseball is compressed from raw metal. A body having a higher mass will have a high density in a constant amount of volume. Non-metals do not hold this property.Īn object’s density is its mass by volume. Raw copper can be attained and then purified and wrapped into a coil. A small metal paperclip can be shaped just with bare hands.Īs mentioned earlier, ductility is the property of metals that allows it to be drawn into thin wires. For instance, if a piece of metal is hit with a mallet and deformation takes place, it is considered malleable. The word malleability means that metal elements can be deformed by exerting a certain amount of stress. Gas and non-metals do not have the property of lustre.Īnother quality of metals is malleability. More or less all metals, metalloids and transition metals are lustrous. When ice melts and becomes water, it does not go back to its solid shape automatically but becomes a viscous liquid.Īn element’s lustre is defined by the way it behaves when light falls on it. Here, many physical properties are seen to get changed, like shape and viscosity. Consider if you have folded a hundred rupee note, the note is still the same chemically. No one can see this change visually you have to use a thermometer or other apparatus to measure it.Ĭhange in the shape of an object can take place, and yet it may remain fixed to its original composition. Similarly, if the pan is kept idle on a cupboard, it will become cold. However, if you touch it, then only can you feel the heat, and it may even cause a burn. You will not see any change in the shape, texture, colour, etc. Suppose if you have put an empty pan on a burning gas oven. You cannot notice a change in temperature until there is any change of state. This is an example of a temporary change. In fact, you can again paint it with some other colour. By painting a metal object, it does not have any effect on the composition of the same. However, for a chemical reaction, change in colour is generally a sign that a reaction is taking place. For example, changing the colour of a metal does not alter its physical properties. For instance, if a wooden piece undergoes sanding, waxing and polishing, it will have a completely different texture than its initial state which was of a rough wood piece.Ĭolour change does not indicate a chemical change. Physical properties consist of several other features of a product, and they are:Īny alteration in the above mentioned physical properties is counted as a physical change.Ī substance’s texture can vary with a physical change. Some examples of temporary change are lighting of a bulb, heating a rod, changing of ice into water, etc. They are also known as temporary changes because the change takes place for a particular period. The changes which are restricted to changes in the display, but no change occurs in the composition is called a physical change. So, what are physical and chemical changes? You need to know their differences in detail, not just for your examination, but also to understand other vital topics in this standard and the future. However, on a larger front, changes are classified into two categories physical and chemical change. They can be period, non-periodic, natural or man-made. Every day you experience a variety of changes around yourself starting from days turning into nights to cooking food, buring of fuel, etc.
0 Comments
Leave a Reply. |