Answer:
[tex]\boxed{\text{25 da}}[/tex]
Explanation:
Step 1. Convert pounds to milligrams
(a) Pounds to grams
[tex]\text{Mass} = \text{2 lb} \times \dfrac{\text{454 g}}{\text{1 lb}} = \text{910 g}[/tex]
(b) Grams to milligrams
[tex]\text{Mass} = \text{910 g} \times \dfrac{\text{1000 mg}}{\text{1 g}} = \text{910 000 mg}[/tex]
Step 2. Calculate the time
(a) Milligrams to minutes
[tex]t = \text{910 000 mg}} \times \dfrac{\text{20 min}}{\text{500 mg}} = \text{36 000 min}[/tex]
(b) Minutes to hours
[tex]t = \text{36 000 min} \times \dfrac{\text{1 h}}{\text{60 min}} = \text{610 h}[/tex]
(c) Hours to days
[tex]t = \text{ 610 h} \times \dfrac{\text{1 da}}{\text{24 h}} = \text{25 da}[/tex]
It will take [tex]\boxed{\textbf{25 da}}[/tex]to dissolve the iron oxide.
Answer : The time taken for the reaction is 36363.64 minutes.
Explanation :
First we have to convert the mass of iron oxide from milligram to pounds (lbs).
[tex]1\text{ lbs}=453592mg[/tex]
or,
[tex]1mg=\frac{1}{453592}\text{ lbs}[/tex]
As, [tex]1mg=\frac{1}{453592}\text{ lbs}[/tex]
So, [tex]500mg=\frac{500mg}{1mg}\times \frac{1}{453592}\text{ lbs}=0.0011\text{ lbs}[/tex]
Now we have to calculate the time taken for the reaction.
As, [tex]0.0011\text{ lbs}[/tex] of iron oxide take time = 20 minutes
As, [tex]2\text{ lbs}[/tex] of iron oxide take time = [tex]\frac{2\text{ lbs}}{0.0011\text{ lbs}}\times 20\text{ minutes}=36363.64\text{ minutes}[/tex]
Therefore, the time taken for the reaction is 36363.64 minutes.
