A chemist must prepare of sodium hydroxide solution with a pH of at . He will do this in three steps: Fill a volumetric flask ab
out 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. Round your answer to significant digits.
1 answer:
The question is incomplete, the complete question is:
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.
Answer:
9g of NaOH
Explanation:
First, the POH must be obtained from the given pH so that we can use this POH to obtain the hydroxide ion concentration. When we obtain the hydroxide ion concentration, as shown in the image, we can now use it to find the mass of sodium hydroxide required to prepare the standard solution since we have the volume of the solution in liters and we can calculate the molar mass of sodium hydroxide to be 40gmol-1. All these steps are shown in the image attached.
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The given reaction is not spontaneous.
We must recognize changes in oxidation states that take place across elements in order to balance these equations. To accomplish this, keep in mind following guidelines:
A neutral element on its own has an oxidation number of zero.For a neutral molecule, the total number of oxidations must be zero.The net charge of an ion is equal to the sum of its oxidation numbers.In a compound: hydrogen prefers +1, oxygen prefers -2, fluorine prefers -1.In a compound with no oxygen present the other halogens will also prefer -1.One of the mercury atoms is oxidized from +1 to +2 in the simple aqueous ion, for a loss of 1 electron.
Oxidation half-reaction:
→
The other mercury is reduced from +1 to zero in mercury metal, for a gain of 1 electron.
Reduction half-reaction:
→
This is a disproportionation redox reaction !
Net reaction:
→
The cell potential is negative so this reaction is NOT spontaneous.
To learn more about the non spontaneous reaction please click on the link brainly.com/question/20358734
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Answer: (1) It is exothermic and DH equals -91.8 kJ.
Explanation:
There are two types of reactions in terms of heat:
Endothermic reactions are those reactions in which heat is absorbed by the system and exothermic reactions are those reactions in which heat is released by the system.
As the heat is given on the products side, it means the heat is released in the reaction and thus the reaction is exothermic. The enthalpy change for exothermic reaction is written as negative and the enthalpy change for endothermic reaction is written as positive.