Ashley-Ann Burnett October 4, 2015
Lab #3: Acids, Bases & pH SLS43-14/7-8
Pre-Lab Questions:
1) An isotope is an atom with a different atomic weight due to changes in the number of neutrons in the nucleus. Some examples of isotopes are Protium, Deuterium, and Tritium, which are all Hydrogen atoms. Instead of the zero neutrons Hydrogen has in its Protium form, Deuterium and Tritium have two and three neutrons respectively. This change in neutron number and therefore atomic weight classify these atoms as isotopes of the element Hydrogen. An ion is an atom with a charge due to changes in the number of electrons (negatively charged particles) in the atom. Ions that have lost electrons have a positive charge, and are called cations. Ions that have gained electrons have a negative charge, and are known as anions. Examples of this would be the ions involved the chemical reaction that creates table salt. In this reaction Sodium (Na) gives its single valence electron to Chlorine (Cl) creating one Na+ cation and one Cl- anion that chemically bond due to the attraction between their opposite charges. An acid is a substance in which the concentration of hydronium ions is greater than the concentration of the hydroxide ions in the substance. An example of this would be HCl (hydrochloric acid). A base is the opposite, as the concentration of hydroxide ions in the substance is greater than the concentration of hydronium ions. An example of a base is CaCO3 (Calcium Carbonate), which is used as an anti-acid in medicines such as Tums. Neutralization is a type of double replacement reaction in which an acid reacts with a base in order to produce a pH neutral substance (water) and a salt. An example of a neutralization reaction is HCl + NaOH NaCl + H2O, which is hydrochloric acid plus sodium hydroxide yields salt and water. A buffer is a compound that generally maintains a constant pH within a solution. If the concentration of hydronium ions is too high the buffer combines with H+ ions reduce their number. If the concentration is too low, the buffer releases H+ ions in order to increase the hydronium concentration. Some examples of buffers are HCO3 (bicarbonate) and H2CO3 (carbonic acid). 2) The pH scale indicates the acidity or basicity of a substance by measuring the concentration of Hydronium ions in the substance. …show more content…
A buffer maintains the pH level of a substance by releasing or accepting H+ ions to adjust the concentration within the substance. It contains both a base and an acid in order for it to react with either added H+ or OH- ions. Take for example the following chemical equation: HCO3 + H+ → H2CO3. In this equation the buffer bicarbonate encounters H+ ions or an acidic substance containing these ions and bonds with them in order to form carbonic acid. This reduces the number of free acidic H+ ions and restores the pH to a more basic level. In the other case where a basicity of the substance is increased, a buffer like carbonic acid is used. Take this equation for example: H2CO3 + OH- → HCO3- + H2O. In this case, carbonic acid reacts to the OH- ions from a basic substance and produces bicarbonate and water. The carbonic acid released H+ ions in order to increase the acidity of the solution, and those ions joined with the OH- ions reducing their number and forming water. Another type of buffer is a citrate
Lab #3: Acids, Bases & pH SLS43-14/7-8
Pre-Lab Questions:
1) An isotope is an atom with a different atomic weight due to changes in the number of neutrons in the nucleus. Some examples of isotopes are Protium, Deuterium, and Tritium, which are all Hydrogen atoms. Instead of the zero neutrons Hydrogen has in its Protium form, Deuterium and Tritium have two and three neutrons respectively. This change in neutron number and therefore atomic weight classify these atoms as isotopes of the element Hydrogen. An ion is an atom with a charge due to changes in the number of electrons (negatively charged particles) in the atom. Ions that have lost electrons have a positive charge, and are called cations. Ions that have gained electrons have a negative charge, and are known as anions. Examples of this would be the ions involved the chemical reaction that creates table salt. In this reaction Sodium (Na) gives its single valence electron to Chlorine (Cl) creating one Na+ cation and one Cl- anion that chemically bond due to the attraction between their opposite charges. An acid is a substance in which the concentration of hydronium ions is greater than the concentration of the hydroxide ions in the substance. An example of this would be HCl (hydrochloric acid). A base is the opposite, as the concentration of hydroxide ions in the substance is greater than the concentration of hydronium ions. An example of a base is CaCO3 (Calcium Carbonate), which is used as an anti-acid in medicines such as Tums. Neutralization is a type of double replacement reaction in which an acid reacts with a base in order to produce a pH neutral substance (water) and a salt. An example of a neutralization reaction is HCl + NaOH NaCl + H2O, which is hydrochloric acid plus sodium hydroxide yields salt and water. A buffer is a compound that generally maintains a constant pH within a solution. If the concentration of hydronium ions is too high the buffer combines with H+ ions reduce their number. If the concentration is too low, the buffer releases H+ ions in order to increase the hydronium concentration. Some examples of buffers are HCO3 (bicarbonate) and H2CO3 (carbonic acid). 2) The pH scale indicates the acidity or basicity of a substance by measuring the concentration of Hydronium ions in the substance. …show more content…
A buffer maintains the pH level of a substance by releasing or accepting H+ ions to adjust the concentration within the substance. It contains both a base and an acid in order for it to react with either added H+ or OH- ions. Take for example the following chemical equation: HCO3 + H+ → H2CO3. In this equation the buffer bicarbonate encounters H+ ions or an acidic substance containing these ions and bonds with them in order to form carbonic acid. This reduces the number of free acidic H+ ions and restores the pH to a more basic level. In the other case where a basicity of the substance is increased, a buffer like carbonic acid is used. Take this equation for example: H2CO3 + OH- → HCO3- + H2O. In this case, carbonic acid reacts to the OH- ions from a basic substance and produces bicarbonate and water. The carbonic acid released H+ ions in order to increase the acidity of the solution, and those ions joined with the OH- ions reducing their number and forming water. Another type of buffer is a citrate