In 1928, 1.0 g of Re was isolated from 660 kg of the ore molybenite. The percent by mass of this element in the molybenite was:
1.5 x 10 ^-4 %
How to set this up, given that 600 kg equals 660,000 g. And Avogadro's number 6.022x10^23?
You didn't ask a question. By the way, the ore is molybDenite and the element, Mo, is molybDenum (without the capital letters, of course).
To calculate the percent by mass of Re in molybenite, you can use the following steps:
1. Determine the mass of Re in grams: Since 1.0 g of Re was isolated from 660 kg of molybenite, we know that the mass of Re is 1.0 g.
2. Calculate the total mass of molybenite in grams: Since 660 kg is equivalent to 660,000 g, the total mass of molybenite is 660,000 g.
3. Calculate the percent by mass of Re in molybenite: Divide the mass of Re (1.0 g) by the total mass of molybenite (660,000 g) and multiply by 100. This can be expressed as:
(1.0 g ÷ 660,000 g) × 100 = 0.00015%
Therefore, the percent by mass of Re in molybenite is 0.00015% or 1.5 x 10^-4 %.
To set up the problem, we need to find the percent by mass of Re in the molybenite ore. We have been given that 1.0 g of Re was isolated from 660 kg (660,000 g) of the ore.
First, we need to calculate the mass of Re in the molybenite ore. We can do this by setting up a proportion using the given values:
1.0 g Re / x kg molybenite = 660 g Re / 660,000 g molybenite
To solve for x, we cross-multiply:
660 g Re * x kg molybenite = 1.0 g Re * 660,000 g molybenite
Rearranging the equation to solve for x gives:
x = (1.0 g Re * 660,000 g molybenite) / 660 g Re
Next, we need to convert the mass of molybenite from grams to kilograms. We know that 600 kg is equal to 660,000 g. This gives us a conversion factor of:
1 kg / 1000 g
We can substitute this into our equation to convert the mass of molybenite to kilograms:
x = (1.0 g Re * 660,000 g molybenite / 660 g Re) * (1 kg / 1000 g)
Simplifying the equation:
x = (1.0 * 660,000 / 660) * (1 / 1000) kg
x = 1000 kg
Now we have the mass of molybenite in kilograms, which is equal to 1000 kg.
Finally, we can calculate the percent by mass of Re in the molybenite. The formula for percent by mass is:
Percent by mass = (mass of element / mass of compound) * 100
In this case, the mass of Re is 1.0 g and the mass of the compound (molybenite) is 1000 kg (converted from g to kg). Plugging in these values, we get:
Percent by mass = (1.0 g / 1000 kg) * 100
Calculating the percent by mass gives us:
Percent by mass = 1.0 x 10^-4 %
Therefore, the percent by mass of Re in the molybenite is 1.0 x 10^-4 %.