How would you confirm that a colourless liquid given to you is pure water

Pure water:- • Pure water is a tasteless and colourless liquid. • If a colourless liquid boils at 100 ° C ( 373 K ) and freezes at 0 ° C ( 273 K ) both at 1 atmospheric pressure, we can say that the given liquid is pure water. • This is because, pure water has a boiling point of 100 ° C ( 373 K ) and a freezing point of 0 ° C ( 273 K ) . Therefore, if a colourless liquid boils has a boiling and melting point of 100 ° C ( 373 K ) and 0 ° C ( 273 K ) at 1 atm respectively, then we can say that the liquid given to you is pure water.

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Hint: Each pure substance has its characteristic melting point and boiling point. Melting points and boiling points are altered if any impurity is present in the substance. Pure water is the only colorless liquid which does not leave any residue after evaporation. Boiling point of water is 100 degree Celsius at atmospheric pressure Melting point of water is 0 degree Celsius at atmospheric pressure Complete solution step by step: Water: Water is a colorless and tasteless liquid. The molecules of water have extensive hydrogen bonds which results in high melting and boiling points. Boiling point Boiling point is a temperature at which the liquid is converted into a vapour at atmospheric pressure. A temperature at which the vapour pressure of the liquid becomes equal to the atmospheric pressure of the liquid’s environment is called the boiling point of that liquid. Each chemical substance has unique bond energy and structure and therefore each chemical substance has unique boiling point. Melting Point At atmospheric pressure, when solid changes to liquid state at particular temperature, this temperature is known as melting point. It is a unique characteristic property of liquid. If a colorless and tasteless liquid is given to us, we can measure its boiling point and melting point. If boiling point is 100 degree Celsius and melting point is 0 degree Celsius then it confirms that the liquid is pure water. Note: Capillary tube is used to determine melting point. When a substance ...

Take a sample of colourless liquid and put on stove if it starts boiling exactly at 1 0 0 ∘C then it is pure water. Any other colourless liquid such as vinegar always have different boiling point. Also observe carefully that after some time whole liquid will convert into vapour without leaving any residue.

Here we have given NCERT Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure. Board CBSE Textbook NCERT Class Class 9 Subject Science Chapter Chapter 2 Chapter Name Is Matter Around Us Pure Number of Questions Solved 21 Category NCERT Solutions NCERT Solutions for Class 9 Science Chapter 2 Is Matter Around Us Pure INTEXT Questions Question 1. What is meant by a pure substance? Solution: A pure substance is one which is made up of only one kind of atoms or molecules. Ex:water is made up of only one kind of particles. So water is a pure substance, Question 2. List the points of differences between homogeneous and heterogeneous mixtures. Solution: Homogeneous mixture Heterogeneous mixture (1) A mixture in which different constituents are mixed uniformly. A mixture in which different constituents are not mixed uniformly. (2) It cannot have physically distinct parts. It has physically distinct parts. (3) The constituents cannot be easily seen. The constituents can be easily seen. (4) The constituents cannot be easily separated. The constituents can be easily separated. (5) Examples :Sugar solution, soda water, soft drinks, vinegar, air etc. Examples :Sugar and sand mixture, milk, ink, paint, wood, blood etc. Question 3. Differentiate between homogeneous and heterogeneous mixtures with examples. Solution: Homogeneous mixture Heterogeneous mixture (1) A mixture in which different constituents are mixed uniformly. A mixture in which different constituents are not mixe...

• Every liquid has a fixed boiling point. Pure water has a boiling point of 100 º C , or 373 K . • Hence, to verify if the colourless liquid is pure water, we will boil it and observe its boiling point . • The boiling point of water varies with atmospheric pressure. • If the liquid starts boiling at a sharp 100 º C , or 373 K , then the colourless liquid will be pure water. • Evaporate the colourless liquid on a low flame. If no residue is left and boiling strictly at 100 ° C then, it is pure water.

By boiling the given colourless water, we can check thewater is pure or not. If the water boils at 100 ° Cthen it is pure water but if its boiling point increases or decreases the water must have some impurities and thus, we can say that the given colourless liquid is not pure.Water is always considereda solvent.

How would you confirm that a colorless liquid given to you is pure water? A very easy solution is to take a sample of colourless liquid and put on stove if it starts boiling exactly at 100 ºC then it is pure water. Any other colourless liquid such as vinegar always have different boiling point. Also observe carefully that after some time whole liquid will convert into vapour without leaving any residue. Now are there any other ways to understand? $\begingroup$ BP would only be a crude indication of purity. A measurement of 100 ºC is only good to 1% relative. It is easy to measure ppm levels of chemicals in water. So you'd need to measure BP to 100.0000 ºC. With that sort of precision a correction for the ambient atmospheric pressure would be needed. $\endgroup$ Measurement of If you can, partially freeze your solution in a kitchen freezer, stir well, then measure the temperature while stirring. Since the freezing point of water is relatively insensitive to atmospheric pressure, you don't have to worry about correcting for the elevation where you live. This method is commonly used as a quick way to check the A shortcut, or as a further check, if you have plenty solution to spare you could take a portion and add enough crushed ice that it doesn't all melt upon stirring. If you get the same value ($$, I'll bet my house that it's water. You could measure various physical properties of the unknown liquid and compare the results to literature values for pure water or to measurem...

Take the steam that is coming out of a boiling water and allow it to cool down, it condenses to form water and on further cooling of this water we get ice. (3) On applying pressure and reducing temperature we can liquefy gases or change them into solid. Example: Take carbon-dioxide gas, reduce its temperature and apply lot of pressure on it so that it changes into solid carbon dioxide, called diy ice, which is used as refrigerant for cooling. If the pressure on it is decreased it directly changes into gas. In LPG cylinders, the petroleum gas is cooled and with lot of pressure changes it into liquid state. While using this LPG, we release the pressure exerted on it and hence it comes out in the form of gas. Question 2. Explain giving examples the various factors on which rate of evaporation depends. Answer : The rate of evaporation depends on the following factors: (1) Surface area: If the surface area is increased the rate of evaporation also increases. (a) To dry the clothes we spread them to dry faster. (b) Tea in saucer cools faster than in a cup. (2) Temperature: If the temperature is increased the rate of evaporation also increases. Due to increase in temperature the particles gain more kinetic energy and change their phase from liquid to gaseous. Water will evaporate faster in sun than in shade. (3) Humidity: It is the amount of water vapour present in air. The air can hold definite amount of water vapour, at a given temperature. If the amount of water vapour is high...

Q. (i) Name the metal: (a) Which can be easily cut with a knife? (b) Which forms amalgams? (c) Which has no fixed shape? (d) Which has a low melting point? (e) Which is yellow in colour? (ii)Classify the following as chemical or physical changes: (a) Cutting of trees (b) Melting of butter in a pan (c) Rusting of almirah (d) Boiling of water to form steam (e) Passing electric current through water and the water breaking down into hydrogen and oxygen gases (f) Dissolving common salt in water (g) Making a fruit salad with raw fruits (h) Burning of paper and wood Physical Change Chemical Change (a) Cutting of trees (c) Rusting of almirah (b) Melting of butter in a pan (e) Passing electric current through water and the water breaking down into hydrogen and oxygen gases (d) Boiling of water to form steam (f) Dissolving common salt in water (g) Making a fruit salad with raw fruits (h) Burning of paper and wood Q. (i) Which of the following can be separated by using a separating funnel and which cannot be separated by using a separating funnel? Give reason. (a) Water and kerosene mixture (b) Water and acetone mixture. (ii)Classify the following into elements, compounds and mixtures. (a) sodium (b) soil (c) sugar solution (d) silver (e) calcium carbonate (f) tin (g) silicon (h) coal (i) air (j) soap (k) methane (l) carbon dioxide (m) blood Q. (i) Define the following : (a) Sol (b) Aerosol (c) Emulsion (d) Foam Give one example of each. (ii) How are sol, solution and suspension diff...