You can easily make basic chemical solutions both at home and at work and in different ways; whether you want to make them from a powdered compound or by diluting another liquid, you can easily determine the correct doses of each substance and solution to use. Remember to wear personal protective equipment when working with chemicals to avoid injury.
Steps
Method 1 of 4: Use the Percentage Weight to Volume Ratio
Step 1. Define the percentage ratio between weight and volume of the solution.
A percent solution is expressed as parts per hundred. Here is an example by weight: a 10% solution by weight means that you have dissolved 10g of solute in 100ml of liquid.
For volume: A 23% solution by volume is a liquid in which there are 23 ml of compound in 100 ml of solution
Step 2. Identify the volume of the solution you want to prepare
To determine the required mass of the compound you must first determine the total volume of liquid you want to obtain, which in turn is defined by the dose you need to perform a certain task, how often you intend to use the solution and its stability over the course. weather.
- For example, make a 5% solution of NaCl in 500ml of water.
- If the solution is to be "fresh" each time you use it, only prepare the amount you need at that time.
- If the solution is stable over the long term, you can make a larger volume of it and keep it for future use.
Step 1. Calculate the mass in grams of solute
To know the dose needed to obtain a certain concentration, you have to carry out a multiplication using the formula: grams = (desired percentage) (desired volume / 100 ml); the percentage must be expressed in grams and the volume in milliliters.
- For example, suppose you want to make a 5% solution of NaCl in 500ml of water.
- Grams = (5) (500ml / 100ml) = 25g.
- If the sodium chloride is already in liquid form, you need to add 25 ml of NaCl instead of 25 g of powdered compound and subtract that volume from the final one; in other words, you have to pour 25 ml of liquid NaCl into 475 ml of water.
Step 2. Weigh the mass of the compound
Once the required dose has been calculated, you must weigh it using a calibrated scale on which you have placed a plate and zeroed the tare. Measure the necessary mass in grams and set it aside.
- For example, make a 25g dose of NaCl.
- Always clean the saucer of the scale of any traces of dust before continuing.
Step 1. Dilute the solute in the proper amount of solvent
Unless otherwise noted, the compound is typically diluted or dissolved in water. Use a graduated cylinder or other similar tool to prepare the desired volume of liquid; stir the powdered solute into the liquid until it dissolves completely.
- For example, mix 500ml of water and 25g of NaCl to make a 5% solution.
- Remember that if you use a liquid compound, you must subtract its volume from the solvent you use: 500ml - 25ml = 475ml of water.
- Add a clear, visible label to the container stating both the concentration and the chemicals it contains.
Method 2 of 4: Prepare a Molar Solution
Step 1. Identify the molecular mass of the compound you are using
This value is expressed in grams / mole (g / mol) and is indicated on the bottle of the substance; if the molecular mass is not listed on the container, you can search online and find that number.
- The molecular mass of a compound is the mass in grams of one mole of the compound itself.
- For example, that of sodium chloride (NaCl) is 58.44 g / mol.
Step 2. Define the volume of the solution you want to make by expressing it in liters
It is very easy to prepare 1 liter of solution, since the molarity is expressed in moles / liter; however, the solvent dose may vary slightly depending on the intended use of the solution. You must use the final volume of the liquid to calculate the number of grams of solute needed to prepare a molar solution.
- For example, prepare a 50 mL solution with a 0.75 molar concentration of NaCl.
- To convert milliliters to liters, divide the number by 1000 and you get 0.05 liters.
Step 3. Calculate the dose in grams you need to obtain a solution at the defined molar concentration
In this case, you have to take advantage of the equation: grams = (desired volume) (desired concentration) (molecular mass). Remember that the volume must be indicated in liters, the concentration in moles over liters and the molecular weight in grams over moles.
- For example, if you want to make a solution of 50 ml of NaCl (molecular mass equal to 58.44 g / mol) with a molar concentration of 0.75 mol / l, you can calculate the amount in grams of solute.
- Grams = 0.05 l * 0.75 mol / l * 58.44 g / mol = 2.19 g of NaCl.
- When you delete the various units of measurement, only the grams of compound should remain.
Step 4. Weigh the mass of solute you need
Use a properly calibrated scale and determine the dose of compound. Place the saucer on the scale and reset the tare before proceeding; add the substance until you reach the correct weight.
- For example, it doses 2.19 g of NaCl.
- When finished, remember to clean the measuring tool.
Step 1. Dilute the powder in a suitable amount of solvent
Most solutions are made using water, unless otherwise specified. The volume of the liquid must be equal to the one you used to calculate the mass of the solute; mix the latter into the solvent until the powder has dissolved completely.
- For example, you can measure 50ml of water using a graduated cylinder (or similar instrument) and add 2.19g of sodium chloride to it.
- Mix everything until the powder is completely dissolved.
- Clearly label the container indicating the molar concentration and the name of the compounds present to easily recognize the solution in the future.
Method 3 of 4: Dilute Solutions with Known Concentrations
Step 1. Define the concentration of each solution
When you proceed with the dilution, you need to know the concentration of each substance you are working with and the final one you want to achieve. This method is very useful for diluting highly concentrated solutions.
Suppose you want to make 75 ml of a solution with a concentration of 1.5 M of NaCl starting from that with a concentration of 5 M; in other words, you have a starting solution with a concentration of 5 M and you want to reduce it to 1.5 M
Step 2. Determine the final volume of the solution
You also need to know the amount of liquid you want to get. You will need to calculate the starting solution dose that you need to add to dilute it to the desired concentration and volume.
For example: prepare 75 ml of a solution with a concentration of 1.5 M of NaCl starting from a liquid with 5 M
Step 3. Calculate the volume of concentrated liquid you need to add to the final solution
For this process you have to use the formula: V.1C.1= V2C.2; V.1 is the volume of the initial liquid and C1 its concentration; V.2 is the final volume to be obtained and C2 its concentration.
- For example: make 75 ml of 1.5 M NaCl solution starting from a 5 M liquid.
- To calculate the necessary volume of the starting liquid, you need to change the arrangement of the terms and solve for V.1: V1 = (V2C.2) / C1.
- V.1 = (V2C.2) / C1 = (0, 075 l * 1.5 M) / 5 M = 0, 225 l.
- Convert the volume from liters to milliliters by multiplying the number by 1000: 22.5ml.
Step 4. Subtract the volume of the starting liquid from that of the final solution
When diluting a solution, you need to make sure you get the correct volume of liquid; by subtracting the amount of liquid to be diluted from the total amount, you ensure that you proceed correctly and obtain the desired concentration.
In the example, you have to obtain a final solution of 75 ml by adding 22.5 ml of liquid to be diluted; accordingly: 75 - 22.5 = 52.5ml. This is the amount of liquid thinner you need to use
Step 5. Mix the two substances in the quantities you just calculated
Use a graduated cylinder (or other similar instrument) and measure out the amount of liquid to be diluted before pouring it into the diluent.
- Always considering the previous example, measure 22.5 ml of starting solution with a concentration of 5 M of NaCl and pour them into 52.5 ml of water; mix to even out the mixture.
- Apply a label to the container stating both the concentration and the name of the compound: 1.5 M NaCl.
- Remember that if you have to dilute an acid in water, you must always pour the substance into the water.
Method 4 of 4: Use Appropriate Security Measures
Step 1. Put on Personal Protective Equipment (PPE)
When working with strong chemicals and solutions you need to make sure your body is safe from harm; It is essential to wear a lab coat, closed-toed shoes, protective eyewear, and gloves when handling these compounds.
- Use a lab coat made from flame retardant fibers.
- Glasses should be equipped with side splash guards.
Step 2. Work in a ventilated area
When you mix the solutions, volatile gases can form which diffuse into the air. Some vapors can only be managed by laboratory fume hoods; if you are working at home, open the windows and turn on a fan to ensure air circulation.
Step 3. Add the acid to the water
When you dilute strong acid substances you must always pour these into the water and not vice versa. The combination of these two substances generates an exothermic reaction (which releases heat) and it can even trigger an explosion if you pour the water into the acid.
Review all safety precautions whenever you work with acid products
Advice
- Do some research before you begin; knowledge is power!
- Try using commonly used chemicals; do not proceed with too complicated mixtures. If you think the result could be dangerous, it probably will be!
Warnings
- Never mix ammonia with bleach.
- Wear protective gear, safety glasses, plastic apron, and neoprene gloves if necessary.
