The Effect of Different Substances on the Freezing Point of Water Ess

The Effect of Different Substances on the Freezing Point of Water Ess The Effect of Different Substances on the Freezing Point of Water Period 4 January 19, 2012 The Effect of Different Substances on the Freezing Point of Water Introduction Water is essential for all life on Earth and covers 70% of the Earth surface. Water is a chemical substance composed of two hydrogen atoms bonded to one oxygen atom. Its chemical formula is H2O. Pure water is transparent, colorless and odorless. Water is mostly seen as liquid. However water can be found in all three states of liquid, solid, and gas depending on the temperature. At room temperature, water is a liquid. But it becomes solid (ice) when the temperature drops to 0oC or it turns into gas when the temperature rises to 100oC. The reason water changes its state is molecules have energy. Water molecules in a liquid form have more energy than in a solid form. They move around quickly. When the liquid cools down, water molecules slow down their movement and the energy is reduced. When the water temperature reaches around 0oC, the molecules almost do not move and stick together to form a solid ice (Manahan, 2010). When water and ice are in contact with each other, two things happen that (1) ice molecules escape into the water (melting) and (2) water molecules are captured on the ice surface (freezing). When the rate of freezing is the same as the rate of melting, the amount of water and the amount of ice do not change. The ice and water are said to be in dynamic equilibrium. The balance point between freezing and melting of the two states of water is at 0oC (Wolf, 2010). But this balance between freezing and melting can easily be disrupt when either water or ice changes conditions. Baking soda, better known to chemists as bicarbonate of soda, sodium bicarbonate, sodium hydrogen carbonate, or sodium acid carbonate, is a chemical compound with a chemical formula of NaHCO3. Baking soda is a white solid and often appears as a fine powder with crystalline grains. Baking soda can form naturally. However, most baking soda sold in stores are man-made by combining carbon dioxide (an odorless gas) and soda ash (extract from sources like a mineral called trona and ashes of certain plants). As baking soda is formed by combining an acid (carbonic) and sodium hydroxide, it reacts with other chemicals as a mild alkali. Therefore, when it is mixed with acid, baking soda neutralizes the acid, breaks down proteins, and gives off carbon dioxide gas (commonly seen as bubbles) (Zukowski, 2009). Because of its chemical and physical properties, baking soda is used for a wide range of applications such as baking, cleaning, deodorizing, buffering, and fire extinguishing. Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of ionic salts. Salt is in a crystalline form but varies in color from colorless when it is pure to white, gray or brownish due to other natural mineral elements within the crystal. Salt is formed naturally and can be found everywhere in the world like underground and sea. There are many different types of salts. Salt is not only essential for human and animal lives but also often used to assist in various manufacturing and productions like textile dyeing, soap making and pottery production (Roman et al, 2011). When a substance like baking soda or salt is put into water, it is dissolved in the water. This is because the polarity of water molecules can attract the polar ionic compounds and separate the molecules of other substances. In this process, scientists term the substance to be dissolved as a solute and refer the water as the solvent the one that does the dissolving. The formed mixture is called a solution (Amora and Chu, 2010). Research has found that the freezing point of a solution is lower than 0oC, the freezing point of the pure water. This is because the added solute disrupts the equilibrium of the water states of liquid and solid. There are fewer water molecules in the solution as some of the water has been replaced by the solute (Senese, 2010). This means that the number of water molecules able to be captured by