• 4 months ago
Transcript
00:00hi kids today we will learn more on physical and chemical changes so let's
00:10get started let's first learn about chemical changes it leads to the
00:17formation of new types of matter that may look totally different from the
00:24original matter example ash and smoke are produced when wood is burned and
00:34they look totally different from wood chemical changes results in the
00:42formation of a new chemical substance or substances example ash is chemically
00:52different from wood and is produced in the process of burning wood chemical
01:00change leads to making or breaking of bonds between atoms of the matter at the
01:09molecular level because of which new chemical substances are formed a
01:16chemical change cannot be reversed example you cannot turn ash back to wood
01:25another example you cannot convert a rotten egg or any fruit back to its
01:33fresh state baked biscuits cannot be converted back to dough rusted iron
01:42cannot be converted back to original iron cooked eggs cannot be converted
01:51back to raw eggs now let's learn about some signs of chemical changes color
02:02change if there is change in the color of the object it suggests a chemical
02:10change example sun tanning makes the color of skin darker as melanin is
02:20produced so it's a chemical change baking of cookies changes the color of
02:29cookie to darker brown color so it's a chemical change rusting of iron changes
02:39the color of iron to brown or red so it's a chemical change smell chemical
02:48changes may give off some smell example when garbage rots it gives off a bad
02:56smell a new physical property is produced after a chemical change example
03:07when an apple rots it becomes softer when piece of wood is burnt its residue
03:17is softer and brittle and also reduces in size some gas is produced when you
03:27burn something smoke is produced so signs of chemical changes are change in
03:37the color of substance release some smell in new physical properties
03:45produced and some gas is released now let's see some chemical changes rusting
03:57of iron where iron oxide is formed burning of gasoline where water vapors
04:06and carbon dioxide are formed cooking eggs bread rising milk souring sun
04:21tanning all these are examples of chemical changes now let's learn more
04:29about physical changes changes that just change the form or physical
04:39appearance of matter like change in the shape size or form and it does not change
04:47the amount of matter in an object and no new substance is produced such changes
04:57are called physical changes and most of the physical changes are reversible but
05:06not all during a physical change molecules are rearranged but their
05:15internal structure is not affected now let's see some examples of physical
05:23changes whipping egg whites is a physical change as just air is forced
05:33into the fluid but no new substance is produced magnetizing a compass needle is
05:43a physical change as no new substance is produced there is just a realignment of
05:53iron atoms boiling of water is a physical change as there is no change in
06:03the molecules of water there's still water the molecules just move faster
06:12when the water boils but there is no actual change so it's a physical change
06:21dissolving sugar in water is a physical change as sugar molecules remain the
06:29same but they are just dispersed within the water dicing potatoes is a physical
06:38change as no new substance is formed while cutting potatoes folding of paper
06:47is a physical change only the shape of paper is changed crushing of paper is a
06:57physical change cutting of an apple it is also a physical change as only the
07:05shape and size of the apple is changed but there is no chemical change in the
07:11apple so kids today we learned more about physical changes and chemical
07:20changes now you may go ahead and take a quiz to learn more bye-bye