Water Activity Lab

Water is a medium for metabolic reactions and an important constituent of cells. In most plants and animals, it makes up about 65-95% of their mass. The water molecule is referred to as a dipole, a polar molecule, with a positive (hydrogen) and negative (oxygen) charge, separated by a very small distance. A molecule with a separated charge is polar. A hydrogen bond; the weak attractive force between a hydrogen atom with a partial positive (o+) charge and an atom with a partial negative charge (o-) oxygen can be formed between two atoms. Hydrogen bonds are weak, however in large quantities, like the large number present in water it makes the molecules difficult to separate and gives water a wide range of physical properties vital to life.

The purpose of this experiment was to see if a penny could hold more drops of salt water or tap water. It was found that a penny could hold an average of 22.3 drops of tap water and only 20.8 drops of salt water. These results are consistent with the hypothesis: If the salt concentration of water impacts the amount of water a penny holds, then the penny will hold less drops with salt water. While dropping the water onto the penny, it was observed that the water formed into a dome-like shape on the penny. It looked like the individual drops of water turned into one large drop of water. This was observed for both the tap and salt water. This happened due to the cohesion and surface tension of water. Cohesion simply means that water molecules are attracted to each other and want to cling together. Surface tension is the special term that is applied to the cohesion of water molecules.

Water (H2O) is a good solvent because it is partially polarized. The hydrogen ends of the water molecule have a partial positive charge, and the oxygen end of the molecule has a partial negative charge. This is because the oxygen atom holds on more tightly to the electrons it shares with the hydrogen atoms. The partial charges make it possible for water molecules to arrange themselves around charged atoms (ions) in solution, like the sodium (Na+) and chloride (Cl−) ions that dissociate when table salt dissolves in water.

Attraction between water molecules which allows insects and other objects to float a top the water

1. Polar molecules A. have bonds with an unequal distribution of electric charge. B. must form ions in water solution. C. have bonds with an equal distribution of electrical charge. D. have bonds with an overall negative charge.

Answer: Mg2+ has 10 electrons. A Magnesium atom has 12 electrons, 2 of which are valence electrons. The atom will lose the 2 outermost electrons in order to stabilize its electron shell. The nucleus maintains its 12 protons and becomes a Mg2+ ion.

As a result of the water molecule bond, each (hydrogen; oxygen) has a slightly negative charge and each (hydrogen; oxygen) has a slightly positive charge.

| After hydrochloric acid is added the mg reacts violently with bubbles and heat. Left over is a clear residue.

Gas molecules bounce and spread out, when solid molecules stick together. When you fill a glass with water, it stays in the glass without it spilling. The glass’ molecules are tightly bonded together which cause there to be no cracks. But if you drop the glass, it will shatter the bindings and all the water will pour out.

Magnesium will react with hydrochloric acid, because it is higher in the reactivity series than hydrogen. The magnesium displaces the hydrogen in the acid, so it forms magnesium chloride and hydrogen gas.

Chapter 2 Essential Questions Describe the properties of water and why water has these properties. Water has unique properties because of its bonds with hydrogen. In a water molecule, there is an oxygen atom bonded with two hydrogen atoms. The oxygen side has more electrons than the hydrogen side, giving the molecule a slightly positive side and a slightly negative side, making a water molecule polar. The polarity of a water molecule gives it properties like cohesion, adhesion, and being a universal solvent.

7. Could this property of water explain why a small paper clip can float on water in a glass that is so full that the water is just about ready to spill out? Explain. A small paper clip can float on water in a glass that is so full that the water is just about ready to spill out since the amount of mass of paper clip is inferior than it resembles to

Because water is polar, water can only ‘adhere’ to other polar substances. After the water on the penny has spilled over. On a molecular scale, the hydrogen bonds are being broken. After completing this experiment, we concluded that due to the amphipathic properties of the soap detergent, the penny would not be able to hold as many drops as a penny without the soap. Again, this is because soap is non-polar and in order for water (water is polar) to ‘mix’ with another substance, that other substance has to be polar as

1) Water molecule is formed with 2 hydrogens and one oxygen atom. Water molecule is a polar molecule because both the opposite side of the molecule have opposite charges. And also, atoms are linked by covalent bonds.

Water is a polar molecule made up of on atom of hydrogen and two atoms of