Water and its properties – solution components and testing of substances’ solubility
that water at room temperature is a colourless and odourless liquid;
that water is a chemical compound made up of particles;
that polar covalent bonds are present between the hydrogen atoms and the oxygen atom in water molecule;
that water circulating in nature forms solutions of various chemical composition.
how to determine a solvent and a solute using examples;
to give examples of substances that dissolve and do not dissolve in water;
to carry out an experiment, the goal of which is to investigate solubility of a given substance.
Components of a water solution
Watch demonstration performed by your teacher or carry out the experiment “Dissolving sugar in water”. Then give a definition of a solution, determining the solvent and the solute.
beaker,
glass rod,
teaspoon,
water,
sucrose (food sugar).
Fill the beaker with tap water about ¾ full.
Put 1 teaspoon of sugar into the beaker with water and mix them using a glass rod. Observe the changes.
All solutions are made up of the following components: solventsolvent and solutessolutes.
Testing the solubility of various substances in water
Before you watch the video “Testing the solubility of various substances in water”, write down a research question and a hypotheses. Note your observations and write down your conclusions after watching the video.
Film dostępny na portalu epodreczniki.pl
Film przedstawia doświadczenie pokazujące rozpuszczalność różnych substancji w wodzie. Do przeprowadzenia doświadczenia użyto: mąkę pszenną, skrobię, piasek cukier, kredę, sól, sodę, benzynę, alkohol, ocet winny, białko jajka i olej słonecznikowy oraz zlewki z wodą, łyżkę i mieszadło. Chlorek sodu, sacharoza, soda oczyszczona, ocet spożywczy, spirytus rozpuszczają się w wodzie, podczas gdy mąka pszenna i ziemniaczana, piasek, kreda, benzyna, olej nie rozpuszczają się w wodzie. Olej i gaz unoszą się na powierzchni wody, podczas gdy mąka, kreda i piasek spadają na dno zlewki. Białko jaja tworzy nieprzezroczysty roztwór z wodą.
Are all substances soluble in water?
Select one of the presented hypotheses, and then verify it.
Not all substances are soluble in water.
All substances are soluble in water.
beakers,
water,
sodium chloride (edible salt),
sucrose (food sugar),
baking soda,
oil,
vinegar,
wheat flour,
potato flour,
petrol,
chalk,
sand,
egg white,
spirit.
Testing of solid substances and materials: put a small teaspoon of tested substance into the beaker with water, mix them with a glass rod; assess the ongoing changes.
Testing of liquid substances and materials: add several cmIndeks górny 33 of tested liquid into the water in a beaker, mix them with a glass rod; observe the ongoing changes.
Different substances vary in terms of solubility in water. Some dissolve in water very well and form a true solution, for example sodium chloride or sucrose (the main ingredient of sugar). There are also substances that dissolve in water not that well and form suspensions, e.g.: potato starch, silica (sand), chalk. When trying to dissolve egg white in water, we will end with a colloidal solution.
List the components of the mixtures written on the flashcard. Check the answer by turning the flashcard over with a click.
| tea | a mixture of water, sugar and tea essence |
| air | a mixture of nitrogen, oxygen and other gases |
| mineral water | a mixture of water and mineral salts |
| dough | raw dough is a mixture of for example flour, eggs, milk and sugar |
| soup | a mixture of water, vegetables, fat and spices |
Fill in the definition below.
...................... mixtures are the ones the components of which are not visible to the naked eye or using simple optical devices. They are also called ............ solutions, simple solutions or — in general — ...................
Which of the following definitions is a definition of a solution:
- a substance dissolved in a solvent
- a liquid that can form a solution after being mixed with a solid, other liquid or gas (its quantity is often greater)
- homogeneous mixture which is made up of a solvent (dispersion medium) and at least one solute (dispersed phase)
- a mixture of a solid and liquid the components of which are visible to the naked eye
Summary
All solutions are made up of a solvent and a solute.
In a solution the quantity of solvent is greater than the quantity of solute.
Substances differ in terms of their solubility in water.
Keywords
solvent, solute, solution, solubility
Glossary
rozpuszczalnik – składnik roztworu; najczęściej jest to substancja występująca w przewadze
substancja rozpuszczona – składnik roztworu, substancja rozpuszczona w rozpuszczalniku