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A pharmacist needs to obtain a 70% alcohol solution. How many ounces of a 30% solution must be mixed with 40 ounces of an solution to obtain a 70% solution?
A mother solution or a pure can be diluted down to give a lower solution; but you can't dilute down to give a higher concentration, i.e. to go from 30%...
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A mixture of gases contains $"H"_2$ and $"O"_2$ gases in the ratio of $"1:4 w/w"$. What is the molar ratio of two gases in the mixture?
All you have to do here is to convert the mass ratio to a mole ratio by using the conversion factor that takes you from grams to moles or vice...
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Asample of a compound contains 0.150 mol C, 0.105 mole H, 0.0300 mol O, and 0.0450 mol N. The molecular mass of the compound is found to be 402 g/mol. What is the compound's chemical formula?
Step 1. Calculate the empirical formula. The empirical formula is the simplest whole-number ratio of atoms in a compound. The ratio of atoms is the same as the ratio of...
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A carbon compound contains 12.8% of carbon, 2.1% of hydrogen and 85.1% of bromine. The molecular weight of the compound is 187.9. What is the molecular formula of the compound?
(Atomic weight: H = 1.008, C = 12.0, Br = 79.9)
As always with these problems, it is useful to assume $100*g$ of unknown compound....and thus find an empirical formula... $"Moles of carbon"=(12.8*g)/(12.011*g*mol^-1)=1.066*mol.$ $"Moles of hydrogen"=(2.1*g)/(1.00794*g*mol^-1)=2.084*mol.$ $"Moles of bromine"=(85.1*g)/(79.90*g*mol^-1)=1.066*mol.$ And we...
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A compound contains only an unknown metal and chlorine. If analysis shows 41.65 grams of the compound contain 14.18 grams of chlorine, what is the % of the metal in the compound?
To find the percentage of the metal, first determine the difference between the mass of the compound and the mass of chlorine. This will give the mass of the metal....
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A compound contains only $C$, $H$, and$ N$. Combustion of $35.0$ $mg$ of the compound produces $33.5$ $mg$ $CO_2$ and $41.1$ $mg$ $H_2O$. What is the empirical formula of the compound?
We can write an equation for the (complete) combustion of the substance as follows: $C_xH_yN_z + (x+y/2+z)/2O_2 to xCO_2+y/2H_2O+zNO_2$ That might look complicated, but all we're saying is that each...
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A compound that contains only nitrogen and oxygen is 30.4% N by mass; the molar mass of the compound is 92 g/mol. What is the empirical formula and the molecular formula of the compound?
In $100* g$ of this there are $30.4* g$ $N$, and the balance $O$. We divide thru by the atomic masses in order to approach the empirical formula: $(30.4*g)/(14.01*g*mol^-1)$ $=$...
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Another compound found on Mars contains iron and oxygen. The compound contains 70% by mass of iron and 30% by mass of oxygen. How do you calculate the empirical formula of this compound?
Your ultimate goal here is to figure out the smallest whole number ratio that exists between iron and oxygen in this unknown compound, i.e. the empirical formula of the compound....
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)A compound that contains just C, H and N is burned in oxygen. When 5.000 g of the compound is burned in excess oxygen, 6.019 g of $CO_2$, 4.313 g of $H_2O$, and 9.438g of $NO_2$ are the only products. What is the empirical formula of the compound?
We must calculate the masses of $"C, H"$, and $"N"$ from the masses of carbon dioxide, water, and nitrogen dioxide. $"Mass of C" = 6.019 color(red)(cancel(color(black)("g CO"_2))) × "12.01 g...
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A certain volume of argon gas ( Mol.wt = 40) requires 45 s to diffuse through a hole at a certain pressure and temperature. The same volume of another gas of unknown molecular weight requires 60 s to pass through the same hole under same conditions?
since kinetic energy of every gases dipends only from the absolute temperature (Ek = KT) and then at a certain temerature is equal for every gasses, and kinetic energy is...
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