Cyberlink Uchiha Chemistry

Yield In chemistry, yield, also referred to as reaction yield, is the amount of product obtained in a chemical reaction. The absolute yield can be given as the weight in grams or in moles (molar yield). The percentage yield (or fractional yield or relative yield), which serves to measure the effectiveness of a synthetic procedure, is calculated by dividing the amount of the obtained desired product by the theoretical yield (the unit of measure for both must be the same): The theoretical yield is the amount predicted by a stoichiometric calculation based on the number of moles of all reactants present. This calculation assumes that only one reaction occurs and that the limiting reactant reacts completely. However the actual yield is very often smaller (the percent yield is less than 100%) for several reasons: Ø   Many reactions are incomplete and the reactants are not completely converted to products. If a reverse reaction occurs, the final state contains both react...

pH Scale and Usage Indicator Theoretical basis The concept of acids and bases is based on several properties which are represented by a group of their aqueous compounds. Based on the properties shown, the acid is a compound that has a sour taste, and redacts the blue lacmus. Bases are compounds that have a bitter taste, and can brighten the red litmus. In aqueous solution, the acid produces H ⁺ and alkaline ions to produce OHˉ ions (Basic Chemical Practicum Guide, 2012: 56). The ion concentration [H ⁺ ] and the concentration of [OHˉ] in water, acid or base solution are very small numbers. Therefore, a chemist named Sorensen proposes a concept called PH (P means Potential and H is a symbol of the Hydrogen element) PH is defined mathematically as follows: PH = - Log [H ⁺ ] For PH in the environment: Ø   Acid: PH <7 Ø   Bases: PH> 7Neutral: PH = 7 (Tony Bird, 1987: 71) Acids and bases are chemicals that are present in everyday life. Citrus juice and ...