what are pure substances ? give two examples of pure substances. - matter
what are pure substances ? give two examples of pure substances.
pure substances are made up of same type of particles or atoms. all the elements and compounds are pure substances because they contain the same kinds of particles. examples: hydrogen, carbon dioxide
**Pure substance – ethyl alcohol, oxygen, carbon, distilled water mixture – blood, steel** hey there! as answered previously:-
crystallization is the process of slow precipitation of solid
crystals of a substance from a concentrated homogeneous solution it
is basically a separation method in which a substance is
transferred from the liquid (i e solution) phase to the solid state
the substance is thus obtained in pure crystalline form and has no
impurity it is used by chemists for the purification of solid
substances
following is an example of using crystallization to obtain pure
copper sulphate from an impure sample
1) take a small amount (5 g) of an impure sample of copper
sulphate in a china dish
2) dissolve the sample in 10 ml of water (we basically have to
use minimum amount of water in order to prepare a saturated
solution)
3) then, filter it to remove impurities
4) evaporate the filtrate on a water bath till small crystals
are formed indicating that a concentrated solution has been
obtained
5) after this, cover the solution with a filter paper and leave
it undisturbed at room temperature for the rest of the day
![](https://img-nm%20mnimgs%20com/img/study_content/lp/1/9/8/114/318/760/662/5-6-08_sonali_9_chemistry_9%202%202%202%201_gsx_sg_ss_html_3c9d32fa%20png)
it will be observed that crystals of pure copper sulphate are
obtained and the impurities are left behind in the solution the right option is d) pure reason: saturn has some unique characteristic like :-1. saturn has rings around it, these rings are made up of rocks, ice and dust.2. density of saturn is less than that of water (density is mass per unit volume), i.e. it is very light so if there were large enough ocean saturn would float on it. 1. introduction: rough surface in contact i. surface of engineering materials: generals  surfaces have chemical properties, which are different from bulk virgin material. o most metallic surfaces in air have oxide layers, which change the chemical and mechanical properties of the surfaces.  surfaces have mechanical properties, which are different from bulk material. o machining or sliding contact makes strain hardened (or work hardened) layer and highly deformed layer, whose strength are different from bulk.  real engineering surfaces are rough. mirror like smooth surface afm image surety, fact, innocence, exactness, success, achievement, validity, exactitude, strength, certainty, truth, morality, goodness, accuracy, righteousness, blamelessness, reality, infallibility, virtuousness, correctness, actuality, irreproachability, right, inerrancy, preciseness, guiltlessness, virtue, behavior, precision, honesty, obedience, strictness, faultlessness, correction, perfection. images photos vector graphics illustrations videos… color . transparent black and white. related images: bathroom sink faucet plumbing water 168 free images of bathroom sink. 55 75 5. bathroom sink faucet. 55 71 4. bathroom clean faucet. 114 139 19. bathroom luxury. 128 139 16. bathroom… 168 free images of bathroom sink chemistry 1010 study guide classify the following properties as intensive or extensive: intensive- doesn’t change (boiling point, temp, color, density, hardness) extensive- changes in size/ amount (volume, mass length scientific method terms experiment: a well-controlled procedure used to obtain data in order to describe a phenomenon. law: a statement that describes natural phenomenon by summarizing collected facts. observation: a statement describing a natural phenomenon that we sense. scientific fact: a statement that is explained by reproducible experimental data hypothesis: guesses that is not verified yet. mass and weight mass is a measurement of the quantity of matter in an object, whereas weigh is a measurement of the force of gravity on the matter of an object; ther we’re being asked which of the following conditions occurs when a chemical change happens to a piece of wood let’s first define a physical change and a chemical change.physical change → there is a change in a matter as it goes from one physical state to another.chemical change → atoms rearrange themselves to create a new substance. now, let’s take a look at each condition:[readmore]a. is splitsplitting wood is only reducing its size. physical changeb. is paintedpainting wood is only placing paint on top of it and not really affecting the composition of the wood.  physical changec. decaysdecaying changes the integrity of the wood itself and transforms it into things like soil. chemical changed. is cutcutting wood is only reducing its size. physical changea chemical change occurs when a piece of wood c. decays. answer: the molecular mass of an element is defined as the sum of the masses of the elements present in the molecule. molecular mass is obtained by multiplying the atomic mass of an element with the number of atoms in the molecule and then adding the masses of all the elements in the molecule. o2 is a diatomic molecule. the mass of an oxygen atom = 16 amu. ∴ mass of o2 molecule = 2 × 16 = 32 amu. mass of one molecule of oxygen → 32/ avogadro constant ( 6.023 × 1023) → 5.31 × 10-23g.