how do I prepare 50% and 70% ethanol from 95% ethanol?
I assume the 50% and 70% are v/v. If so, then, 95% ethanol means you have 95 mL ethanol in a total volume of 100 mL (which doesn't necessarily mean the volume of water is 5.0 mL).To get 50 mL ethanol (from the 95% stuff) you need (50/95)*100 = 52.63 mL. (You can see that 52.63 mL (of 95% stuff) x 0.95 = 50 mL of PURE ethanol. Then add water to 100 mL total volume. For 70%, you need (70/95(*100 = approximately 75 mL.
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To prepare 50% and 70% ethanol solutions from 95% ethanol, you will need to dilute the 95% ethanol with distilled water. Here is a step-by-step guide:
Preparing 50% Ethanol Solution:
Step 1: Calculate the amount of 95% ethanol needed. Let's say you want to prepare 100 mL of the final 50% ethanol solution.
Amount of 95% ethanol = (Volume of final solution) * (% of ethanol) / (Final % of ethanol)
= 100 mL * 50% / 95%
≈ 52.63 mL
Step 2: Measure 52.63 mL of 95% ethanol.
Step 3: Add distilled water to make up the total volume of the solution.
Volume of distilled water = (Volume of final solution) - (Volume of 95% ethanol)
= 100 mL - 52.63 mL
≈ 47.37 mL
Step 4: Mix the measured 52.63 mL of 95% ethanol with 47.37 mL of distilled water. This will give you a 50% ethanol solution.
Preparing 70% Ethanol Solution:
Step 1: Calculate the amount of 95% ethanol needed. For this example, let's say you want to prepare 200 mL of the final 70% ethanol solution.
Amount of 95% ethanol = (Volume of final solution) * (% of ethanol) / (Final % of ethanol)
= 200 mL * 70% / 95%
≈ 147.37 mL
Step 2: Measure 147.37 mL of 95% ethanol.
Step 3: Add distilled water to make up the total volume of the solution.
Volume of distilled water = (Volume of final solution) - (Volume of 95% ethanol)
= 200 mL - 147.37 mL
≈ 52.63 mL
Step 4: Mix the measured 147.37 mL of 95% ethanol with 52.63 mL of distilled water. This will give you a 70% ethanol solution.
Remember to handle ethanol solutions carefully, as they are flammable.
To prepare a solution of a specific concentration from a higher concentration, you need to understand how to calculate the ratios of the desired concentrations.
To prepare a 50% ethanol solution from 95% ethanol:
Step 1: Understand the concept
In this case, you are diluting the original solution with water. The equation you need to use is:
C1V1 = C2V2
Where:
C1 = Initial concentration (95%)
V1 = Volume of the initial solution (unknown)
C2 = Final concentration (50%)
V2 = Final volume of the solution (unknown)
Step 2: Calculate the volumes
Using the equation above, you can rearrange it to solve for V1:
V1 = (C2V2) / C1
Given the values C1 = 95%, C2 = 50%, and let's consider V2 as 100 mL (you can adjust this as per your requirement), you can calculate V1 as follows:
V1 = (50% * 100 mL) / 95%
V1 = 52.63 mL
Therefore, to prepare a 50% ethanol solution, take approximately 52.63 mL of 95% ethanol and dilute it with water to make a total volume of 100 mL.
To prepare a 70% ethanol solution from 95% ethanol:
Step 1: Calculate the volumes
Using the same equation, rearrange it to solve for V1:
V1 = (C2V2) / C1
Given the values C1 = 95%, C2 = 70%, and V2 = 100 mL, you can calculate V1 as follows:
V1 = (70% * 100 mL) / 95%
V1 = 73.68 mL
Therefore, to prepare a 70% ethanol solution, take approximately 73.68 mL of 95% ethanol and dilute it with water to make a total volume of 100 mL.