What is the molarity of a solution of 14.0 g NH4Br in enough H2O to make 150 mL of solution?
2 answers:
Explanation:
Molarity is defined as the number of moles per liter of solution.
Mathematically, Molarity =
Since it is given that the molarity of a solution of 14.0 g and volume is 150 mL or 0.15 L.
Whereas number of moles =
So, molar mass of is 97.94 g/mol.
Thus, number of moles =
= 0.142 mol
Therefore, calculate the molarity as follows.
Molarity =
=
= 0.946 mol/L
Hence, we can conclude that molarity of the solution is 0.946 mol/L.
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Answer:
Aluminum metal
Explanation:
In order to properly answer this or a similar question, we need to know some basic rules about galvanic cells and standard reduction potentials.
First of all, your strategy would be to find a trusted source or the table of standard reduction potentials. You would then need to find the half-equations for aluminum and gold reduction:
Since we have a galvanic cell, the overall reaction is spontaneous. A spontaneous reaction indicates that the overall cell potential should be positive.
Since one half-equation should be an oxidation reaction (oxidation is loss of electrons) and one should be a reduction reaction (reduction is gain of electrons), one of these should be reversed.
Thinking simply, if the overall cell potential would be obtained by adding the two potentials, in order to acquite a positive number in the sum of potentials, we may only reverse the half-equation of aluminum (this would change the sign of E to positive):
Notice that the overall cell potential upon summing is:
Meaning we obey the law of galvanic cells.
Since oxidation is loss of electrons, notice that the loss of electrons takes place in the half-equation of aluminum: solid aluminum electrode loses 3 electrons to become aluminum cation.