1 Answers
Call
A block of wood is floating in water. The weight of the part of the block above water is one third of the total weight of the block. What is the the part the water by the block of weight of wood, using Archimedes' principle?
The question is not clear but I think this is likely what you are looking for. If $2/3$ of the block of wood is submerged then $color(white)("XXX")$the mass of water...
1 Answers 1 views
Do molecular substances tend to have LOWER densities than non-molecular substances?
In a molecular compound, there is little intermolecular force between molecules. Gases, certainly molecular materials, in which the space between molecules is vast, are inherently LOW materials. On the other...
1 Answers 1 views
What is the difference between molecular weight and formula weight?
Some do not exist as individual molecules. For example, there is no such thing as a molecule of sodium chloride. That's why it is appropriate to use the term formula...
1 Answers 1 views
The molecular formula of lithium carbonate is Li2CO3. What is the molecular weight of this drug?
As you know this salt is commonly used to treat mania. The formula mass is simply the sum of the molar masses of the contributing atoms: i.e. $(2xx6.94+12.011+3xx15.999)*g*mol^-1$ $=$ $??$
1 Answers 1 views
The molecular formula of calcium chloride is CaCl2. What is the molecular weight of this drug?
Weight of $Ca$ = $40$ Weight of $Cl$ = $35.5$ Molecular formula is $CaCl_2$ i.e. $1$ atom of $Ca$ and $2$ atoms of $Cl$. Hence, molecular weight = $"1...
1 Answers 1 views
The atomic weight of Ga is 69.72 amu. There are only two naturally occurring isotopes of gallium: $"^69Ga$ with a weight of 69.0 amu, and $"^71Ga$ with a weight of 71.0 amu. What is approximate natural abundance of the $"^71Ga$ isotope?
Let the percentage of the isotope $""^71Ga$ be $=x%$ Then, The percentage of the isotope $""^69Ga$ is $=(100-x)%$ We write the mass balance equation $100*69.72=x*71+(100-x)*69$ $6972=71x+6900-69x$ $2x=6972-6900=72$ $x=36$ Therefore, The...
1 Answers 1 views
How do we differentiate between a $"molecular element"$, and a $"molecular compound"$? And how are these differentiated from $"non-molecular"$ species?
The distinction between a molecular and non-molecular structure is one of the most important criteria with which to assess . But here, if we have an elemental molecule, we have...
1 Answers 1 views
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...
1 Answers 1 views
Hydrogen peroxide has the empirical formula HO and an empirical formula weight of 17.0 amu. If the molecular weight is 34.0 amu, what is the molecular formula?
First, you want to find the ratio between the empirical formula and molecular formula; that is, how much has the molecular formula been simplified to reach the empirical formula. We...
1 Answers 1 views
A sample of $KClO_3$ on decomposition gives 448 $mL$ of oxygen gas at NTP. Calculate:
(a) Weight of oxygen produced
(b) Weight of $KClO_3$ originally taken
(c) Weight of $KCl$ produced?
Start with the balanced chemical equation for the of potassium chlorate, $KClO_3$ $color(green)(2)KClO_(3(s)) stackrel(color(red)("heat"))(->) color(blue)(2)KCl_((s)) + color(orange)(3)O_(2(g))$ The important thing to notice here is that $color(green)(2)$ moles of potassium chlorate...
1 Answers 1 views