Answer:
Option A. This step is to remove water from the ether layer.
Explanation:
When the goal of an experiment is to conduct a reaction and isolate the product, it is referred to as work-up. The work-up refers to method aimed at purifying the material and most commonly occur in a separatory funnel. Solutions are added to the funnel to either extract or wash the mixture with the goal of isolating the product from excess reagents, catalysts, solvent, side product that may arise from side reactions.
Common washes include: Water, Sodium Bicarbonate, Sodium Carbonate, saturated sodium chloride (brine).
When an organic layer ( e.g. diethyl ether, ethyl acetate) is washed with brine, the purpose of the wash is to REMOVE LARGE AMOUNT OF WATER that may be dissolved in the organic layer.
Brine works to remove water from an organic layer because it is highly concentrated (since Sodium Chloride is highly water soluble. Therefore, the most likely reason for washing a reaction product mixture containing hydrocarbons in diethyl ether with with brine solution in a separatory funnel is to remove the water from the ether layer.
As a general rule of thumb molecules where metals interact with non-metals tend to form ionic bonds (because they form oppositely-charged ions), while molecules where non-metals interact with non-metals tend to form covalent bonds (because they share electrons to fill valence shells). Some of the options listed refer to large polymers of more basic units - if you can identify the basic units, you can get a sense of the kinds of bonds you're dealing with.
Starch is a polymer of glucose. Glucose is an organic molecule made of C, H, and O (all non-metals). It contains COVALENT bonds.
Graphite is a carbon polymer (sort of). Carbon is a non-metal. It contains COVALENT bonds.
Paraffin wax is a mixture of long-chain hydrocarbons (lots of carbons stuck together with some hydrogens stuck around the edges). Non-metals again. COVALENT.
Copper nitrate is a metal (copper) and a non-metal (the polyatomic ion nitrate, NO3-). Therefore, copper nitrate as a whole is IONIC (be careful though - the N and O within the nitrate ion are both non-metals and so are bonded covalently, but they ultimately form an ion that is capable of forming ionic bonds with metals).
Iron oxide is a general term for some combination of iron (a metal) and oxygen (a non-metal). Regardless of the specific combination, the interaction is IONIC.
Sucrose is formed when glucose interacts with another sugar, fructose. Again, only C, H, and O are involved, so the molecule is COVALENT.
Calcium carbonate is similar to the copper nitrate situation - you have a metal (calcium) and a non-metal (carbonate) interacting though an IONIC bond. As with nitrate, carbonate (CO3[2-]) is itself a polyatomic anion containing covalent bonds between the C and O's, but forms ionic bonds because it is ultimately an ion.
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<span>Ba2+(aq)+2I−(aq)+2Na+(aq)+SO2−4(aq)→BaSO4(s)+2I−(aq)+2Na+(aq)
The spectator ions are: </span><span>Na</span>⁺, I⁻.
They appear on both sides of the reaction, hence did not take part in the reaction.
Answer:
Eqv Pt pH = 8.73
Explanation:
HOAc + NaOH => NaOAc + H₂O
50ml(0.10M HOAc) + 50ml(0.10M NaOH) => 100ml(0.05M NaOAc) + H₂O
For neutralized system, 100ml of 0.05M NaOAc remains
NaOAc => Na⁺ + OAc⁻
Na⁺ + H₂O => No Rxn
OAc⁻ + H₂O => HOAc + OH⁻
C(i) 0.05M ----- 0M 0M
ΔC -x ----- +x +x
C(f) 0.05-x
≅ 0.05M ----- x x
Kb = Kw/Ka = [HOAc][OH⁻]/[OAc⁻] = 1 X 10⁻¹⁴/1.7 X 10⁻⁵ = (x)(x)/(0.05M)
=> x = [OH⁻] = SqrRt(0.05 x 10⁻¹⁴/1.7 x 10⁻⁵) = 5.42 x 10⁻⁶M
=> pOH = -log[OH⁻] = -log(5.42 x 10⁻⁶) = 5.27
pH + pOH = 14 => pH = 14 - pOH = 14 - 5.27 = 8.73 Eqv Pt pH
Answer:
D. It is extremely reactive.
Explanation:
Hello!
In this case, since potassium is an alkali metal, it is known those are extremely reactive because the energy required to ionize them is very low, it means they react so easily. For instance, even in the presence of water, potassium is able to react and form a purple flame as a product of the reaction:
As well as potassium, the rest of the elements belonging to the alkali metals series are extremely reactive; therefore the answer is D. It is extremely reactive.
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