Concentration Terms PDF

# Concentration Terms ## 1. Molarity (M) - No. of moles of solute per one liter of solution. - $M = \frac{n}{VL}$ - $ M = \frac{Wt (gm)}{Mut. VL}$ - $Wt = \frac{n * Mut}{fwt}$ ### Solid: - Formula: $Wt = \frac{M * Mut * Vml}{1000}$ ### Example: - NaOH 0.2M in 100 ml - Wt = 0.8 gm...

# Concentration Terms ## 1. Molarity (M) - No. of moles of solute per one liter of solution. - $M = \frac{n}{VL}$ - $ M = \frac{Wt (gm)}{Mut. VL}$ - $Wt = \frac{n * Mut}{fwt}$ ### Solid: - Formula: $Wt = \frac{M * Mut * Vml}{1000}$ ### Example: - NaOH 0.2M in 100 ml - Wt = 0.8 gm ### Liquid: - Formula: $Vstock = \frac{M * Mwt * Vml}{1000 * \% * P}$ ### Example: - HCl 0.5M in 150 ml - Vstock = 5.6gml - Formula: $(MV_1) = (MV_2)$ ## 2. Normality: - No of gram equivalent of solute per one liter of solution - $N = \frac{wt (gm)}{Eqwt * VL}$ - $Eqwt = \frac{Mwt}{X}$ - $X = $ Valence factor ### Acids or Bases: | Solute | X | |-------------------|---:| | HCl | 1 | | NaOH | 1 | | H2SO4 | 2 | | H3PO4 | 3 | | Al(OH)3 | 3 | | CaCl2 | 2 | | (NH4)2CO3 | 2 | | KMnO4 | 6 | ### Solid: - Formula: $Wt(gm) = \frac{N * Mut * Vml}{1000 * X }$ ### Liquid: - Formula: $Vstock = \frac{N * Mut *Vml}{1000 * \% * P * X}$ ## 3. Strength (S) - No. of grams of solute per one liter of solution - Formula: $S = \frac{Wt(gm)}{VL}$ ### Solid: - Formula: $Wt(gm) = \frac{S * Vml}{1000}$ ### Liquid: - Formula: $Vstock = \frac{S * Vml}{1000 * \% * P}$ - $S = M * Mwt = \frac{N * Mwt}{X}$ ## 4. Percentage ### 1. %w/v: - No. of grams of solute per 100 ml of solution - Formula: $%w/v = \frac{Wt of solute (gm)}{Vml of solution} * 100$ ### 2. %v/v: - No. of milliliter of solute per 100 ml of solution - Formula: $%v/v = \frac{Vml of solute}{Vml of solution}* 100$ ### 3. %w/w: - No. of grams of solute per 100 gm of solution - Formula: $%w/w = \frac{Wt(gm) of solute}{Wt(gm) of solution} * 100 $ ### Example: - (0.5 M NaOH) - Wt = 20 gm - % W/v = 10% ## 5. PPM: - No. of miligrams of solute per one liter of solution - Formula: $PPM = \frac{wt(mg)}{VL}$ - Formula: $PPM = \frac{wt (gm) * 10 ^ 3}{VL}$ - Formula: $PPM = S * 10^3$ ### Solid: - Formula: $PPM = \frac{M * Mut * 10^3}{X}$ - Formula: $PPM = \frac{N * Mut *10^3}{X}$ ### Liquid: - Formula: $wt(gm) = \frac{PPM * Vml}{10^3 * 10^3} = \frac{PPM * Vml}{10^6}$ - Formula: $Vstock = \frac{PPM * Vml}{10^6 * \% * P}$ ## 6. PPb: - No. of micrograms of solute per one liter of solution - Formula: $PPb = \frac{wt(Mg)}{VL}$ - Formula: $PPb = \frac{wt(gm) * 10^6}{VL}$ - Formula: $PPb = \frac{PPM * 10^3}{1}$ - Formula: $PPb = S * 10^6$ - Formula: $PPb = \frac{M * Mut * 10^6}{X}$ - Formula: $PPb = \frac{N * Mut *10^6}{X}$ ### Solid: - Formula: $wt(gm) = \frac{PPb * VL}{10^6} = \frac{PPb * Vml}{10^9}$ ### Liquid: - Formula: $Vstock = \frac{PPb * Vml}{10^9 * \% * P}$ ## Chemical Analysis ### Qualitative - Determination of Chemical structure of composition of substance ### Quantitative - Determination of the amount of material in a sample ## Titration - Quantitative Chemical Analysis based on measuring the volume of a standard solution ("titrant") required to completely react with a measured volume of the substance being analyzed ("analyte"). ### Titrant - or Standard - Solution with a known concentration that is added to the analyte. ### Analyte - or Titrand - The unknown solution to be analyzed. ### Indicator - Material added to the analyte solution to give an observable color change at the end point. ## End Point - The point at which the indicator changes its color. ## Volumetric analysis - A category of quantitative chemical analysis based on measuring the volume of a standard solution "titrant" required to completely react with a measured volume of the substance being analyzed "analyte". ## Acid-Base Titration - A type of volumetric analysis based on the reaction between a solution of known concentration of acid and a solution of unknown concentration of base, or vice versa. - Example: Strong Acid - HCl vs NaOH - Strong base - 0.1 M NaOH - 0.1 M HCl ## Preciptation Titration - A volumetric analysis technique in which a standard solution of a precipitant is used to determine the concentration of an analyte. ### Mohr's Method - A method for determining the chloride ion concentration in a sample using a standard solution of silver nitrate (AgNO3) as a precipitant, with potassium chromate K2CrO4 as an indicator. - Equation: $AgNO3 + Cl^- -> AgCl + NO3^-$ - End point: Reddish Brown (from Ag2CrO4) ## Complexometric Titration - A type of volumetric analysis that involves reactions leading to the formation of a complex. ### Complex - A central metal ion surrounded by ligands. - Ligands: Neutral or negatively charged species that carry a lone pair. - Coordination Sphere: Sphere includes the central metal ion and the ligands attached to it. ### Coordination Number: - The number of ligands attached to the central metal ion. ### Types of Ligands: - **Monodentate** - has one position of donation of the lone pair. - **Bidentate** - has two positions of donation of the lone pair. - **Multidentate** - has more than two positions of donation of the lone pair. ## Determination of Conc of Mg2+ - **Direct Titration:** The concentration of Mg2+ can be determined using EDTA as the titrant. This method is relatively simple and involves the use of an indicator (EBT) to detect the endpoint. - **Back Titration:** The concentration of Ca2+ can be determined by back titrating with Mg2+. EDTA is added to a known volume of a Ca2+ solution, forming the complex Ca-EDTA. The unused EDTA is then titrated with a standard Mg2+ solution, again using EBT as the indicator. This allows for a precise measurement of Ca2+ concentration. - **Replacement Titration:** This method is used to determine the concentration of Ca2+ in a solution by using a known volume of Mg-EDTA solution as the titrant. This method involves the reaction of Mg-EDTA with the Ca2+ ions in the solution, displacing Mg2+ from the complex and forming Ca-EDTA. This allows for a convenient way to measure the concentration of Ca2+ ions. - **EDTA:** Ethylenediaminetetraacetic acid a hexadentate chelating agent, which forms stable complexes with metal ions. - EBT: Eriochrome Black T, it changes from blue to red when it is bound to Mg2+. - Ammonia buffer: A solution that helps maintain the pH of a solution. ### End Point Calculation - In Direct Titration: - $MV_{EDTA} = MV_{Mg^{2}+}$ - In Back Titration: - $MV_{EDTA} = MV_{Ca^{2}+} + V(burette) * M_{Mg^{2}+}$ - In Replacement Titration: - $MV_{EDTA} = MV_{Ca^{2}+}$ ### End Point - **Direct Titration:** When the solution changes from red (Mg-EBT) to blue (EDTA), indicating that all Mg2+ ions have reacted with EDTA. - **Back Titration:** When the solution changes from blue to red, indicating that all remaining Mg2+ ions have reacted with EBT - **Replacement Titration:** When the solution changes from red (Mg-EBT) to blue (EDTA), indicating that all free Mg2+ is available to form a red complex, the existing Mg2+ ions have reacted with EDTA and free EBT is present resulting in the blue color of the free EBT indicator.