Describe how you would prepare 2.00 L of each of the followingsolutions. (a) 0.255 M NaOH from solid NaOH Place g NaOHin a L volumetric flask; add water to dissolve the NaOH, and fillto the mark with water, mixing several times along the way. (b) 0.255 M NaOH from 1.00 M NaOH stock solution
Question
Describe how you would prepare 2.00 L of each of the following solutions:
Defining Stock and Dilute Solutions
A stock solution has a high concentration of a particular solute and is used for obtaining moderate quantities of solute using small volumes. A dilute solution is one with a low concentration of a particular solute and is used for dealing with substances by using normal volume instead of small volumes.
Problem 41 Medium Difficulty
Describe how you would prepare 2.00 L of each of the following solutions. a. 0.250 M NaOH from solid NaOH b. 0.250 M NaOH from 1.00 M NaOH stock solution c. 0.100 M K 2 C r O 4 from solid K 2 C r O 4 d. 0.100 M K 2 C r O 4 from 1.75 M K 2 C r O 4 stock solution
Answer
a) Dissolve 20 g of N a O H in 2.00 L of water to form 0.250 M NaOH solution. b) Use 0.5 L of 1.00 M N a O H stock solution and dilute it with water to 2.00 L c) Dissolve 38.84 g of K 2 C r O 4 in 2.00 L of water to form 0.100 M K 2 C r O 4 solution. d) Use 0.114 L of 1.75 M K 2 C r O 4 stock solution and dilute it with water to 2.00 L.
Video Transcript
this question asks us to describe how we would prepare to leaders of each of the following solutions in a it says we want prepare 0.25 Moller and a ohh from solid anyway. H let's start with a concentration 0.25 moment. His 0.25 moles her leader. Multiply this by the volume. We're making a two litre solution. Leaders cancels left like moles.
Problem 37 Medium Difficulty
Describe how you would prepare 2.00 L of each of the following solutions. a. 0.250 M NaOH from solid N a O H b. 0.250 M NaOH from 1.00 M NaOH stock solution c. 0.100 M K 2 C r O 4 from solid K 2 C r O 4 d. 0.100 M K 2 C r O 4 from 1.75 M K 2 C r O 4 stock solution
Answer
a. Place 20.0 g N a O H in a 2 -L volumetric flask; add water to dissolve the NaOH and fill to the mark. b. Add 500. m L of the 1.00 M N a O H stock solution to a 2 - L volumetric flask; fill to the mark with water. c. As in a, instead using 38.8 g K 2 C r O 4. d. As in b, instead using 114 m L of 1.75 M K 2 C r O 4 stock solution.
Video Transcript
for this problem, We're test with solving how to figure out to make various concentrations of solutions of various molecules. First, we want to find how to make two leaders of the 0.25 Moeller anyway solution starting with solid and a witch.
What happens to molarity when you increase volume?
Since molarity is defined as moles of solute per liters of solution, if you increase the volume without changing the number of moles of solute, the molarity will of course decrease. This means that you've successfully diluted the initial solution, i.e. you've made it less concentrated.
Can you use stock solution to prepare a target solution?
As it turns out, you don't have enough moles of solute to prepare your target solution from your stock solution. The only way to prepare your target solution and still use that stock solution is to dissolve more sodium hydroxide in the stock solution.