Full question:
First of all, bear in mind that this question is incomplete. Here is the full question:
- Which of the procedures, if either, is more accurate when making a 1/50 dilution of a solution?
a) Transfer 1 mL with a pipet into a 50-mL volumetric flask.
b) Transfer 20 mL with a pipet into a 1-L volumetric flask.
c) Both procedures have the same accuracy.
- How can the accuracy of either procedure be improved?
a) Use an Erlenmeyer flask instead of a volumetric flask.
b) Use a graduated cylinder instead of a pipet for the transfer.
c) Calibrate each piece of glassware.
d) Instead of using a 1/50 dilution to make the solution, weigh out the material on a balance and transfer ir directly to the volumetric flask.
Answer:
1) c) Both procedures have the same accuracy.
2) c) Calibrate each piece of glassware.
Explanation:
1) Given that the 1/50 relation is maintained whether we pour 1 mL into a 50-mL volumetric flask or we transfer 20 mL with a pipet into a 1-L volumetric flask, both procedures have the same accuracy (because in both procedures we are using volumetric glassware).
When we want the most exact result possible, we need to calibrate the volumetric glassware used (bear in mind that the only volumetric glassware is the buret, the volumetric flask, the micropipet and the pipet). This is usually done measuring the mass of water poured by the recipient or contained in it, and using the density of that liquid to convert mass into volume. In this way is possible, for example, to determine that a pipet poured 10.016 mL and not 10.000 mL.
Answer:
2 pairs (4 electrons)
Explanation:
In a molecule of oxygen there are 2 oxygen atoms. There are 6 electrons in the outer shells of oxygen atoms. When 2 oxygen atoms form a covalent bond they share their electrons. In a diagram this would be represented by the overlap of the two circles representing the outer shells of both oxygen atoms. If each oxygen atom 'puts forward' 2 electrons into the centre, then 4 will be shared overall for each atom, making both atoms have full outer shells of 8 electrons each. 4 electrons make 2 pairs, hence the answer.
Answer:
Well, carbon monoxide can be created from formic acid by adding sulphuric acid which will dehydrate said formic acid:
HCOOH
−
→
−
−
−
H
2
SO
4
CO+H
2
O
HCOOH→HX2SOX4CO+HX2O
Therefore, we can imagine the reverse reaction theoretically, which would make carbon monoxide an acidic oxide. However, the forward reaction does not proceed easily and it needs both the high acidity of sulphuric acid and its strong dehydrative properties to actually work. And your question mentions using hot, concentrated sodium hydroxide to make the reverse one work.
Most oxides that are classified as acidic or basic either have a very electrophilic central atom (e.g.
CO
2
COX2
) which can be attacked by the weak nucleophile water (which in turn can then release an acidic proton), or they have a high charge density on the oxygen which allows it to abstract a proton from water directly. Carbon monoxide is neither. If you check out its molecular orbitals, you will notice that even though carbon is partially positive it has the largest HOMO contribution, meaning a proton would be more likely to attatch to the carbon side — which doesn’t want one at all. The LUMO is, luckily, also more carbon-centred, meaning nucleophilic attacks on carbon are possible. However, it is also degenerate due to the double bond so that an attack is not favoured.
Thus, the carbon monoxide molecule is one that won’t react with water at all and totally defies the concept of acidic/basic oxides.
Abbreviations:
HOMO is a widely used abbreviation for the Highest Occupied Molecular Orbital, i.e. the one with the highest energy that still contains electrons. It is usually the orbital that will attack nucleophilicly or that will be attacked electrophilicly.
LUMO is a widely used abbreviation for the Lowest Unoccupied Molecular Orbital, i.e. the virtual (unoccupied) orbital that has the lowest energy. When considering a nucleophilic attack, the attacking electrons will usually interact with the LUMO. Electrophiles attack with other molecules’ HOMO with their LUMO.
Explanation:
Answer:
Explanation:
We are given the amounts of two reactants, so this is a limiting reactant problem.
1. Assemble all the data in one place, with molar masses above the formulas and other information below them.
Mᵣ: 58.44
NaCl + AgNO₃ ⟶ NaNO₃ + AgCl
m/g: 0.245
V/mL: 50.
c/mmol·mL⁻¹: 0.0180
2. Calculate the moles of each reactant
3. Identify the limiting reactant
Calculate the moles of AgCl we can obtain from each reactant.
From NaCl:
The molar ratio of NaCl to AgCl is 1:1.
From AgNO₃:
The molar ratio of AgNO₃ to AgCl is 1:1.
AgNO₃ is the limiting reactant because it gives the smaller amount of AgCl.
4. Calculate the moles of excess reactant
Ag⁺(aq) + Cl⁻(aq) ⟶ AgCl(s)
I/mmol: 0.900 4.192 0
C/mmol: -0.900 -0.900 +0.900
E/mmol: 0 3.292 0.900
So, we end up with 50. mL of a solution containing 3.292 mmol of Cl⁻.
5. Calculate the concentration of Cl⁻
![\text{[Cl$^{-}$] } = \dfrac{\text{3.292 mmol}}{\text{50. mL}} = \textbf{0.066 mol/L}\\\text{The concentration of chloride ion is $\large \boxed{\textbf{0.066 mol/L}}$}](https://tex.z-dn.net/?f=%5Ctext%7B%5BCl%24%5E%7B-%7D%24%5D%20%7D%20%3D%20%5Cdfrac%7B%5Ctext%7B3.292%20mmol%7D%7D%7B%5Ctext%7B50.%20mL%7D%7D%20%3D%20%5Ctextbf%7B0.066%20mol%2FL%7D%5C%5C%5Ctext%7BThe%20concentration%20of%20chloride%20ion%20is%20%24%5Clarge%20%5Cboxed%7B%5Ctextbf%7B0.066%20mol%2FL%7D%7D%24%7D)
Answer: Natural gas is produced from onshore and offshore natural gas and oil wells and from coal beds.
Explanation:
