A chemist must prepare 0.9 L of sodium hydroxide solution with a pH of 13.40 at 25°C. He will do this in three steps: Fill a 0.9 L volumetric flask about halfway with distilled water. Weigh out a small amount of solid sodium hydroxide and add it to the flask. Fill the flask to the mark with distilled water. Calculate the mass of sodium hydroxide that the chemist must weigh out in the second step.

9.04 g

Explanation:

Given that:

pH of NaOH = 13.40

pOH = 14 - pH

pOH = 14 - 13.40

pOH = 0.6

Now, from there we can find the concentration of NaOH = [OH⁻]

=

=

= 0.2512 M

Given that; volume = 0.9 L

∴ number of moles of NaOH = volume × concentration of NaOH

= 0.9 × 0.2512

= 0.2261 moles

mass of NaOH = number of moles of NaOH × molar mass of  NaOH

mass of NaOH = 0.2261  × 40

mass of NaOH = 9.04 g

a. a clone will be physically identical to the original, but won’t be genetically identical

have a good day!

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.