Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol⋅dm⁻³ in SI unit. A solution with a concentration of 1 mol/L is said to be 1 molar, commonly designated as 1 M. To avoid confusion with SI prefix mega, which has the same abbreviation, small caps ᴍ or italicized M are also used in journals and textbooks. Show Wikipedia Answer Mole Fraction: The mole fraction of a single solute in a solution is simply the number of moles of that solute divided by the total moles of all the solutes/solvents. The mole fraction of solute i is written as Xi. Parts Per Million(PPM) and Parts per Billion (PPB): "Parts per" is a convenient notation used for low and very low concentrations. Generally speaking it is very similar to weight percentage - 1% w/w means 1 gram of substance per every 100 g of sample and it is (although very rarely) named pph - parts per hundred. Other abbreviations stand for:
ppq is more a theoretical construct than a useful measurement, chances are you will never see it in use. Parts per million also can be expressed as milligrams per liter (mg/L). For convenience, this worksheet allows you to select different mass, volume, and concentration units, and the necessary conversions are carried out for you to obtain the value of the blank cell in the desired unit. Note that the unit of molecular weight must be g/mol. Serial Dilution: Serial dilution is a process by which a series of solutions can be made which conserves the amount of chemical needed. The process uses each successively created solution as the stock solution for the next. The calculation is very simple. The Equation:
The equation allows you to calculate how much of the stock solution contains the right amount of moles for the more dilute solution. Note: You can only go from higher to lower concentration. You cannot "concentrate" a solution from lower to higher concentration. The following video runs through the calculations in more detail. Practice Problems: Molarity Calculations Serial Dilutions Worksheet Solutions Practice Problems and Answers Molar concentration (also called molarity, amount concentration or substance concentration) is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol/dm3 in SI unit. A solution with a concentration of 1 mol/L is said to be 1 molar, commonly designated as 1 M. Common symbols cSI unitmol/m3Other units mol/LDerivations from Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution.[1] For use in broader applications, it is defined as amount of substance of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase c {\displaystyle c} :[2] c = n V = N N A V = C N A . {\displaystyle c={\frac {n}{V}}={\frac {N}{N_{\text{A}}\,V}}={\frac {C}{N_{\text{A}}}}.}Here, n {\displaystyle n} is the amount of the solute in moles,[3] N {\displaystyle N} is the number of constituent particles present in volume V {\displaystyle V} (in litres) of the solution, and N A {\displaystyle N_{\text{A}}} is the Avogadro constant, since 2019 defined as exactly 6.02214076×1023 mol−1. The ratio N V {\displaystyle {\frac {N}{V}}} is the number density C {\displaystyle C} . In thermodynamics the use of molar concentration is often not convenient because the volume of most solutions slightly depends on temperature due to thermal expansion. This problem is usually resolved by introducing temperature correction factors, or by using a temperature-independent measure of concentration such as molality.[3] The reciprocal quantity represents the dilution (volume) which can appear in Ostwald's law of dilution. Formality or analytical concentrationIf a molecular entity dissociates in solution, the concentration refers to the original chemical formula in solution, the molar concentration is sometimes called formal concentration or formality (FA) or analytical concentration (cA). For example, if a sodium carbonate solution (Na2CO3) has a formal concentration of c(Na2CO3) = 1 mol/L, the molar concentrations are c(Na+) = 2 mol/L and c(CO2−3) = 1 mol/L because the salt dissociates into these ions.[4] In the International System of Units (SI) the coherent unit for molar concentration is mol/m3. However, this is inconvenient for most laboratory purposes and most chemical literature traditionally uses mol/dm3, which is the same as mol/L. This traditional unit is often called a molar and denoted by the letter M, for example: mol/m3 = 10−3 mol/dm3 = 10−3 mol/L = 10−3 M = 1 mM = 1 mmol/L.To avoid confusion with SI prefix mega, which has the same abbreviation, small caps ᴍ or italicized M are also used in journals and textbooks.[5] Sub-multiples such as millimolar consist of the unit preceded by an SI prefix:
The conversion to number concentration C i {\displaystyle C_{i}} is given by C i = c i N A , {\displaystyle C_{i}=c_{i}N_{\text{A}},}where N A {\displaystyle N_{\text{A}}} is the Avogadro constant. Mass concentrationThe conversion to mass concentration ρ i {\displaystyle \rho _{i}} is given by ρ i = c i M i , {\displaystyle \rho _{i}=c_{i}M_{i},}where M i {\displaystyle M_{i}} is the molar mass of constituent i {\displaystyle i} . Mole fractionThe conversion to mole fraction x i {\displaystyle x_{i}} is given by x i = c i M ¯ ρ , {\displaystyle x_{i}=c_{i}{\frac {\overline {M}}{\rho }},}where M ¯ {\displaystyle {\overline {M}}} is the average molar mass of the solution, ρ {\displaystyle \rho } is the density of the solution. A simpler relation can be obtained by considering the total molar concentration, namely, the sum of molar concentrations of all the components of the mixture: x i = c i c = c i ∑ j c j . {\displaystyle x_{i}={\frac {c_{i}}{c}}={\frac {c_{i}}{\sum _{j}c_{j}}}.}Mass fractionThe conversion to mass fraction w i {\displaystyle w_{i}} is given by w i = c i M i ρ . {\displaystyle w_{i}=c_{i}{\frac {M_{i}}{\rho }}.}MolalityFor binary mixtures, the conversion to molality b 2 {\displaystyle b_{2}} is b 2 = c 2 ρ − c 1 M 1 , {\displaystyle b_{2}={\frac {c_{2}}{\rho -c_{1}M_{1}}},}where the solvent is substance 1, and the solute is substance 2. For solutions with more than one solute, the conversion is b i = c i ρ − ∑ j ≠ i c j M j . {\displaystyle b_{i}={\frac {c_{i}}{\rho -\sum _{j\neq i}c_{j}M_{j}}}.}The sum of molar concentrations gives the total molar concentration, namely the density of the mixture divided by the molar mass of the mixture or by another name the reciprocal of the molar volume of the mixture. In an ionic solution, ionic strength is proportional to the sum of the molar concentration of salts. Sum of products of molar concentrations and partial molar volumesThe sum of products between these quantities equals one: ∑ i c i V i ¯ = 1. {\displaystyle \sum _{i}c_{i}{\overline {V_{i}}}=1.}Dependence on volumeThe molar concentration depends on the variation of the volume of the solution due mainly to thermal expansion. On small intervals of temperature, the dependence is c i = c i , T 0 1 + α Δ T , {\displaystyle c_{i}={\frac {c_{i,T_{0}}}{1+\alpha \Delta T}},}where c i , T 0 {\displaystyle c_{i,T_{0}}} is the molar concentration at a reference temperature, α {\displaystyle \alpha } is the thermal expansion coefficient of the mixture.
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