Which of the following statements holds true for a chemical change? In a chemical change, no new substance is formed. In a chemi
2 answers:
Answer: In a chemical change, the molecular structure of the substance changes.
Explanation:
Chemical change is the change in which chemical composition of the substance changes by rearrangement of atoms. The molecular structure changes due to change in atoms.
Example:
Physical change is a change in which only the physical properties such as size, shape etc change and there is no rearrangement of atoms.
Example: melting of ice
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0.040 mol / dm³. (2 sig. fig.)
<h3>Explanation</h3> in this question acts as a weak base. As seen in the equation in the question,
produces
rather than
when it dissolves in water. The concentration of
will likely be more useful than that of
for the calculations here.
Finding the value of from pH:
Assume that ,
.
.
Solve for :
Note that water isn't part of this expression.
The value of Kb is quite small. The change in is nearly negligible once it dissolves. In other words,
.
Also, for each mole of produced, one mole of
was also produced. The solution started with a small amount of either species. As a result,
.
,
,
.