What is 1 mM in moles?

A mole is a set amount of something, the way a dozen of anything means 12 whether you're talking about a dozen eggs, donuts or months. In chemistry, whether you're talking about the elements iron, sulfur or chromium, a mole of something always refers to the same number of particles such as atoms, molecules, ions or electrons. How many particles? The answer is as many as there are atoms in 12 grams of the isotope carbon-12. Mole, which uses the symbol "mol," is a convenient unit when working with such tiny things as atoms, allowing one to count them in heaps.

Establish the relationship between moles and millimoles. There are 1000 millimoles per mole: 1 mole = 1000 millimoles. Another way of expressing the relationship is 1/1000 moles = 1 millimole. The relationship can also be expressed as a fractional notation: 1 mole/1000 millimoles or 1000 millimoles/1 mole.

Express the relationship as appropriate to your needed outcome, writing it down. A simple conversion might only call for the equation 1 mole = 1000 millimeters, while a scientific calculation likely calls for you to express the relationship on paper as the fractional notation of 1000 millimoles/1 mole.

Calculate the conversion. If using the equation 1 mole = 1000 millimoles, multiply each side of the equation by the amount of moles you are converting. Multiplying each side by the same amount keeps them equal. If using the fractional notation, multiply it by the moles you are converting: "y moles X 1000 millimoles/1 mole" where "y" is the number of moles you are converting.

Things You'll Need

• Pencil
• Paper
• Calculator

Tips

• In conversions, when using fractional notations in the equation, make sure the unit you are converting to is on top: If converting to millimoles, the notation should list millimoles over moles. If converting from millimoles to moles, millimoles should be on the bottom.

  According to current measurements, the number of atoms in 12 grams of carbon-12 is 6.0221376 X 10 to the twenty-third power. That value is known as Avogadro's number.

Warnings

• Avogadro's number, though used as a constant, could change as methods of measurement grow more precise. It changed in the 1980s from a value of 6.022045 X 10 to the twenty-third power. Remember that mole is defined in terms of the number of atoms in 12 grams of carbon-12 isotope, not Avogadro's number.

Related Articles

How to Convert Atoms to Grams

How to Convert AMU to Mole

What is a Mole?

The Conversion Factors Inherent in Chemical Formulas

How to Convert Atoms to Grams

How to Convert Atoms to Grams With a Calculator

How to Convert Grams to Moles

How to Convert Micrograms to Micromoles

Density to Molarity Conversion

How to Calculate the Moles of a Compound

How to Convert Micromolar to PPM

How to Convert Moles to Molecules

How to Find the Number of Grams

What Are Representative Particles of Elements?

How to Convert Grams to AMU

How to Calculate the Number of Moles in a Solution

How to Calculate Moles from Molecular Weight

How to Determine Moles of Solute

How to Calculate the Normality of HCL

Tips

• In conversions, when using fractional notations in the equation, make sure the unit you are converting to is on top: If converting to millimoles, the notation should list millimoles over moles. If converting from millimoles to moles, millimoles should be on the bottom. According to current measurements, the number of atoms in 12 grams of carbon-12 is 6.0221376 X 10 to the twenty-third power. That value is known as Avogadro's number.

Warnings

• Avogadro's number, though used as a constant, could change as methods of measurement grow more precise. It changed in the 1980s from a value of 6.022045 X 10 to the twenty-third power. Remember that mole is defined in terms of the number of atoms in 12 grams of carbon-12 isotope, not Avogadro's number.

About the Author

Sophie Johnson is a freelance writer and editor of both print and film media. A freelancer for more than 20 years, Johnson has had the opportunity to cover topics ranging from construction to music to celebrity interviews.

One mole of carbon is the amount of the substance that has the same number of atoms as in 12 grams of carbon-12, or more specifically 6×10²³ atoms.

A concentration of a solution can be measured in different ways, for example by measuring the ratio between the mass of the solute and the total volume of the solution. Here we consider molar concentration, which is measured as the ratio of the amount of substance in moles to the total volume of the solution. The substance in our case is the solute, while the volume is measured for the entire solution, even if it has other solutes in it. Here the amount of substance is measured as the number of elementary entities (e.g. atoms or molecules) of a substance. Because there are vast numbers of elementary entities even in a small volume of a substance, we use special units called moles for the amount of substance. One mole is defined as the number of atoms in 12 grams of carbon-12, which is about 6×10²³ atoms.

Moles are very convenient to use for substances that are in quantities small enough, that can be easily measured using household or industrial measuring devices. Otherwise, we would need to use either very large numbers or very small quantities (for mass or weight) that are hard to work with and impossible to measure using currently available measuring devices. The elementary particles most commonly used when working with moles are atoms. We can also use moles to measure other particles such as molecules or electrons, but we would need to specify which particles are in use in this case. Molar concentration is also sometimes called molarity.

We have to be careful not to confuse molarity with another related property, molality. Unlike molarity, molality is the ratio of the amount of substance of the solute to the mass of the solvent, and not to the mass of the entire solution. In some cases, values for molarity and molality of a solution are very close. This is the case if our solvent is water, and if the amount of solute is small enough that its mass and volume are insignificant — but this is not always the case.

Weight of one mole of various substances. It can be found using the periodic table.

Changes in Molar Concentration

Molar concentration can be affected by temperature, although this depends on the substances present in this solution. Temperature can cause some solvents to expand, and if the solute does not expand with the solvent, then the molar concentration decreases. It is also possible for the solvent to evaporate while the amount of the solute remains the same, as the temperature increases. In this case, the concentration of the solution will increase. In some cases, the opposite happens. Sometimes raising or lowering the temperature changes the solubility. As a result, all or parts of the solvent stop being dissolved in the solution, and the concentration is decreased.

Units

Molar concentration is measured in moles per unit of volume, for example in moles per liter or moles per cubic meter. The latter is the SI unit. It can also be measured in moles per another unit of volume.

Finding Molar Concentration

To find molar concentration we need to know the amount of substance and the total volume of the solution. To determine the amount of the substance we could use the molecular formula for this substance and information about the mass of this substance that is present in the solution. In particular, to find how many moles of the solution we have, we can look up the atomic mass of each atom present in the molecule in the periodic table, and then divide the total mass of the substance by the total atomic weight of atoms in the molecule. We have to make sure that before we add the atomic masses together, we multiply each of the atomic masses for a specific atom by the number of atoms of this type present in the molecule.

The reverse is also possible. If we know the molar concentration of our solution and the formula of the solute, then we can determine the amount of solvent present in the solution, both in moles and in grams. For this, we will need to check the periodic table for the atomic weights, as described earlier.

Examples

Let us calculate the molarity of a solution that has 3 tablespoons of baking soda mixed with 20 liters of water. 1 tablespoon is about 17 grams, so 3 tablespoons are 51 grams. Baking soda is also known as sodium bicarbonate and its chemical formula is NaHCO₃. We will work with atoms in this example, so let us find the atomic masses for sodium (Na), hydrogen (H), carbon (C), and oxygen (O).

Na: 22.989769
H: 1.00794
C: 12.0107
O: 15.9994

The molar concentration of 1 cube of sugar in one cup of tea is 0.049 moles/liter.

We have O₃ in our formula, therefore we need to multiply the atomic mass of oxygen by 3, getting 47.9982. Now let us add these atomic masses. We will get 84.006609. The atomic masses in the periodic table are generally specified in atomic mass units. This is the case with our data as well. This atomic mass in atomic mass units corresponds to the mass of 1 mole of an element in grams. This means that the mass of 1 mole of NaHCO₃ is 84.006609 grams. We were given 51 grams of soda. Let us find how many moles we have by dividing the total amount of 51 grams by the number of grams in one mole, or 84 grams. We get about 0.6 moles.

This means that we diluted 0.6 moles of baking soda in 20 liters of water. Let us divide this amount of the baking soda by 20 liters to get the molar concentration: 0.6 moles / 20 L = 0.03 moles/L. We got a low concentration because we used such a small amount of soda and diluted it in a large volume of water.

Let us try another example and find a molar concentration of 1 cube of sugar in one cup of tea. Table sugar is made up of sucrose. First let us find the weight of one mole of sucrose, the formula for which is C₁₂H₂₂O₁₁. Using the periodic table we find that the mass of one mole is 12×12 + 22×1 + 11×16 = 342 grams. 1 cube of sugar is 4 grams, which is 4/342 = 0.01 moles. 1 cup is 237 milliliters, so 1 cube of sugar mixed with one cup of tea makes 0.01 moles / 237 milliliters × 1000 (to convert to liters) = 0.049 moles/liter.

Uses

Stoichiometry helps with determining the amounts of substances that react with each other, as well as the amounts of substances that are created through this reaction.

Molar concentration is convenient to use. If the temperature and pressure are the same for all gases, then one mole of each gas occupies the same volume, and we can use this property for different calculations.

For convenience, molar concentration is often used when working with chemical reactions. The branch of chemistry that deals with determining the quantities of initial substances and products of chemical reactions, stoichiometry, often deals with molar concentration. We can find molar concentration by using the chemical formula of the final component that becomes a solute, as we did for the baking soda, but we can also use chemical equations to find it. We will need to know the formulas and the amounts for the substances (reactants) that are being used for our chemical reaction to create the solute as the final product. We will then have to balance the equation to find out the resulting product, and then use the periodic table, as described above, to find the needed information for calculating molar concentration. In this case, we can also do the reverse as well, if we know the molar concentration.

When we start with several substances, which react with each other, we can find the formula for the final product by balancing the equation for the chemical reaction between the substances. If we mix the product of this reaction into a solution, we can find the molar concentration as described in earlier examples.

Let us look at a simple example. We will use baking soda again, and mix it with vinegar for an interesting chemical reaction. You can find these substances easily, you probably already have them in your pantry. The formula for baking soda is NaHCO₃, as we mentioned earlier. Vinegar is not a pure compound, it is a 5% mix of acetic acid in water. The chemical formula for acetic acid is CH₃COOH. The concentration can be smaller, depending on the manufacturer and the country of origin, because different concentrations are considered standard in different countries. We do not have to worry about water in this reaction because water and baking soda do not react with each other.

Let us write and balance the equation for the reaction between baking soda and acetic acid:

NaHCO₃ + CH₃COOH → NaC₂H₃O₂ + H₂CO₃

One of the products of this reaction, H₂CO₃, is unstable and will undergo another reaction:

H₂CO₃ → H₂O + CO₂

So, in the end, we have water (H₂O), carbon dioxide (CO₂), and sodium acetate (NaC₂H₃O₂). We can then mix sodium acetate with water and proceed with calculating the molar concentration, as we did in the earlier example for baking soda. We have to be careful when calculating the volume of the water to account for the water that the acetic acid was mixed with to make vinegar and the water that was a product of the chemical reaction. Sodium acetate is an interesting chemical compound — it is used in heating pads and hand warmers.

When we use stoichiometry to determine either the amount of reactants or the amount of the final product later used in calculations of the molar concentration, we will notice that only a limited amount of one reactant will react with other reactants. This will impact the yield of our final product. Because molar concentration can help us do the “reverse engineering” calculations to find out what amounts of reactants we should start with, it is a useful concept for practical applications, when working with chemical reactions.

Whenever we use a recipe, be it in cooking, when making medication, or even when creating an environment for aquarium fish, we are concerned with concentration. While in everyday life we may prefer working with grams, in chemistry or pharmacy molar concentration is often used.

When making medication that is in contact with membranes in the body, such as eye medication, pharmacists have to match the osmotic concentration of the medicine to the one of the bodily fluids on the other side of the membrane. If this is not done, differences in osmotic concentration may cause the fluid to move across the membrane and result in problems.

In Pharmacy

Molar concentration is important when mixing compounds to create medicine because it influences how this medicine affects the body. Some medications are poisonous if the concentration is too high, and many are not as effective when the concentration is too low. In addition, concentration is important in the fluid exchange between the membranes of the body. Here we can consider the molar concentration or calculate the value for osmotic concentration by using molar concentration. Osmotic concentration is more often used in this context. If a substance on one side of the membrane, for example, medication, has a higher concentration than on the other side of the membrane, for example inside of the eye, then the more concentrated solution will flow into the area with lower concentration. This flow may create problems. For example, if there is a flow of liquid into a cell, such as a blood cell, then the cell may reach its capacity for liquid and break. The flow of liquid out of a cell would be equally problematic because it will interfere with the regular functioning of the cell. Therefore it is generally desirable to match the concentration of the fluid within the target area in the body, such as blood, to the concentration of the medication.

A patient receiving medication from an IV bag on a pole.

A note on conversion between molarity and osmotic concentration: in some cases these values are equal, but not always. It would depend on whether or not substances diluted in the solution have separated into ions in the process called dissociation. This is because osmotic concentration considers particles in general, while molarity considers only a specific type of particles, for example, molecules. So for example, if we consider molecules for the molar concentration, but our substance has separated into ions, then we would have fewer molecules than we would have the total number of particles. As a result, the molar concentration would be lower. We have to be careful and know the physical properties of the solution to be able to convert molar concentration to osmotic concentration.

Pharmacists also have to take into consideration the tonicity of a solution. Tonicity is a related property that depends on concentration. Unlike osmotic concentration, tonicity indicates the concentration of substances in a solution that cannot pass through the membrane in the body under consideration. These substances apply pressure onto the membrane because of osmosis and of their inability to cross the barrier. When medication is designed to enter the bloodstream or any other bodily fluid, pharmacists balance tonicity to ensure that this medication does not cause osmotic pressure.

To ensure the correct tonicity medication is often diluted in a saline solution. This is a solution of table salt (NaCl) in water, made in a concentration that will ensure correct tonicity that matches the internal body fluid when mixed with the medication. It is usually in a sterile container if administered intravenously, or is mixed directly with the medication.

References

Do you have difficulty translating a measurement unit into another language? Help is available! Post your question in TCTerms and you will get an answer from experienced technical translators in minutes.

How many moles are in 1mm?

Is mM the same as mole?

What does mM stand for moles?

How many Millimolar is in a molar?