Hello I have a couple questions first is
How man grams of Fe(OH)3 can be produced by the addition of .25 moles of Fecl3 to 1.2L of a .85M NaOH solution . I know we use the molarity equation MOlarity= moles of solute/ mass of solvent but i keep gettin gthe wrong answer
Also rank from highest to lowest melting point.
a. CH4 b. MgO c. H2O d. H2S
I thought it would be b d a c but i am wrong how can you tell?
1.2L of .85M NaOH contains 1.02 moles NaOH
FeCl3 + 3NaOH = Fe(OH)3 + 3NaCl
But, you only have .25 moles of FeCl, so there is an excess of NaOH, since only 3*.25=.75 moles are needed. That means you will only get .25 moles of Fe(OH)3. Convert that to grams.
Not sure on the melting points, but you should be able to look them up.
ITs the addition of .25
yes -- so the FeCl3 is dropped into the NaOH solution, and it all reacts, right? Am I missing something here?
To solve the first question, let's start by writing a balanced chemical equation for the reaction between FeCl3 and NaOH:
FeCl3 + 3NaOH -> Fe(OH)3 + 3NaCl
From the balanced equation, we can see that the ratio of FeCl3 to Fe(OH)3 is 1:1. This means that for every mole of FeCl3, we will produce one mole of Fe(OH)3.
Given that we have 0.25 moles of FeCl3, we expect to produce 0.25 moles of Fe(OH)3. To convert moles to grams, we need to know the molar mass of Fe(OH)3.
The molar mass of Fe(OH)3 can be calculated by adding up the atomic masses of its elements:
Molar mass of Fe = 55.845 g/mol
Molar mass of O = 15.999 g/mol
Molar mass of H = 1.00784 g/mol
So, the molar mass of Fe(OH)3 = (55.845 g/mol) + 3(15.999 g/mol) + 3(1.00784 g/mol) = 106.867 g/mol.
Now, we can calculate the mass of Fe(OH)3 produced by multiplying the number of moles by the molar mass:
Mass of Fe(OH)3 = 0.25 mol * 106.867 g/mol = 26.71675 g.
Therefore, approximately 26.72 grams of Fe(OH)3 can be produced.
Moving on to the second question about ranking substances from highest to lowest melting point:
To determine the melting point of substances, we need to consider their intermolecular forces. Stated generally, stronger intermolecular forces result in higher melting points.
Let's analyze each compound:
a. CH4 (methane) - Methane is a nonpolar molecule with London dispersion forces being the only intermolecular force present. London dispersion forces are generally weak for nonpolar compounds.
b. MgO (magnesium oxide) - Magnesium oxide is an ionic compound consisting of Mg^2+ cations and O^2- anions. Ionic compounds have strong electrostatic forces of attraction between oppositely charged ions and generally have high melting points.
c. H2O (water) - Water is a polar molecule, and it exhibits hydrogen bonding, which is a particularly strong type of dipole-dipole interaction. Due to hydrogen bonding, water has a higher melting point than expected for a molecule of similar molecular weight.
d. H2S (hydrogen sulfide) - Hydrogen sulfide is a polar molecule, but its boiling and melting points are lower compared to water due to weaker dipole-dipole interactions.
Considering the intermolecular forces, we can now rank the substances from highest to lowest melting point:
Highest melting point: b. MgO (ionic compound)
Moderate melting point: c. H2O (strong hydrogen bonding)
Lower melting point: d. H2S (weaker dipole-dipole interactions)
Lowest melting point: a. CH4 (London dispersion forces)
Therefore, the correct ranking is: b, c, d, a.