Chemistry, 09.09.2021 14:00, 10040816

How can you distinguish between a physical change and a chemical change?

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answered: madelyngv97

Physical Change

When a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged.Physical change is a temporary change.A Physical change affects only physical properties i.e. shape, size, etc.A physical change involves very little to no absorption of energy.Some examples of physical change are freezing of water, melting of wax, boiling of water, etc..In a physical change, no new substance is formed.Physical change is easily reversible i.e original substance can be recovered.

Chemical Change

When a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances..A chemical change is a permanent change.Chemical change both physical and chemical properties of the substance including its compositionDuring a chemical reaction, absorption and evolution of energy take place.A few examples of chemical change are digestion of food, burning of coal, rusting, etc.A chemical change is always accompanied by one or more new substance(s).Chemical changes are irreversible i.e. original substance cannot be recovered.

answered: Guest

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

answered: Guest

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .

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