If you are given the molarity of a solution, what additional information would you need to find the weight/weight percent (w/w%)
1 answer:
Answer:
- The molar mass of the solute, in order to convert from moles of solute to grams of solute.
- The density of solution, to convert from volume of solution to mass of solution.
Explanation:
Hello,
In this case, since molarity is mathematically defined as the moles of solute divided by the volume of solution and the weight/weight percent as the mass of solute divided by the mass of solution, we need:
- The molar mass of the solute, in order to convert from moles of solute to grams of solute.
- The density of solution, to convert from volume of solution to mass of solution.
For instance, if a 1-M solution of HCl has a density of 1.125 g/mL, we can compute the w/w% as follows:
Whereas the first factor corresponds to the molar mass of HCl, the second one the conversion from L to mL of solution and the third one the density to express in terms of grams of solution.
Regards.
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1) 385 J
2) 450 J
Explanation:
1)
The amount of energy that must be absorbed by a certain substance in order to increase its temperature by is given by the equation:
where
m is the mass of the substance
C is its specific heat capacity
is the increase in temperature of the substance
For the block of copper in this problem, we have:
m = 10 g is the mass
is the specific heat capacity of copper
is the change in temperature
So, the energy absorbed by the block of copper is
2)
Similarly for the block of iron, the energy absorbed by the iron is given by
where
m is the mass of the block of iron
C is its specific heat capacity of iron
is the increase in temperature of the block
Here we have:
m = 10 g is the mass of the block
is the specific heat capacity of iron
is the change in temperature
So, the energy absorbed by the block of iron is
Answer:
Choice A: approximately .
Explanation:
Note that the unit of concentration, , typically refers to moles per liter (that is:
.)
On the other hand, the volume of the two solutions in this question are apparently given in , which is the same as
(that is:
.) Convert the unit of volume to liters:
.
.
Calculate the number of moles of formula units in that
of the
solution:
.
Note that (sulfuric acid) is a diprotic acid. When one mole of
completely dissolves in water, two moles of
ions will be released.
On the other hand, (sodium hydroxide) is a monoprotic base. When one mole of
formula units completely dissolve in water, only one mole of
ions will be released.
ions and
ions neutralize each other at a one-to-one ratio. Therefore, when one mole of the diprotic acid
dissolves in water completely, it will take two moles of
to neutralize that two moles of
produced. On the other hand, two moles formula units of the monoprotic base
will be required to produce that two moles of
. Therefore,
and
formula units would neutralize each other at a two-to-one ratio.
.
.
Previous calculations show that of
was produced. Calculate the number of moles of
formula units required to neutralize that
.
Calculate the concentration of a solution that contains exactly
of
formula units:
.