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How does sodium become a negative ion of neon

Svetlanka [38]

I don’t know if this works

8 0

3 years ago

Part IV. Limiting Reactants! A Challenge Problem!

Alexxandr [17]

Answer:

a. Fe2O3(s) + 2Al(s) → 2Fe(s) + Al2O3(s)

b. Fe2O3 is the limiting reactant.

c. 6.30 grams Fe

d. 52.6 %

Explanation:

Step 1: Data given

Mass of iron(III) oxide Fe2O3 = 9.00 grams

Mass of aluminium = 4.00 grams

Molar mass Fe2O3 = 159.69 g/mol

Aluminium molar mass = 26.98 g/mol

Step 2: The balanced equation

Fe2O3(s) + 2Al(s) → 2Fe(s) + Al2O3(s)

Step 3; Calculate Moles

Moles = mass / molar mass

Moles Fe2O3 = 9.00 grams / 159.69 g/mol

Moles Fe2O3 = 0.0564 moles

Moles Al = 4.00 grams / 26.98 g/mol

Moles Al = 0.148 moles

Step 4: Calculate limiting reactant

For 1 mol Fe2O3 we need 2 moles Al to produce 2 moles Fe and 1 mol Al2O3

Fe2O3 is the limiting reactant. It will completely be consumed (0.0564 moles). Al is in excess. There will react 0.0564*2 = 0.1128 moles

There will remain 0.148 - 0.1128 = 0.0352 moles Al

Step 5: Calculate moles Fe

For 1 mol Fe2O3 we need 2 moles Al to produce 2 moles Fe and 1 mol Al2O3

For 0.0564 moles Fe2O3 we'll have 2*0.0564 = 0.1128 moles Fe

Step 6: Mass of Fe

Mass Fe = 0.1128 moles * 55.845 g/mol

Mass Fe = 6.30 grams

Step 7: If you carried out this reaction and it actually produced 0.475 mL of molten iron (r = 6.98 g/mL), what is the percent yield of this reaction?

Density = mass / volume

Mass = density * volume

Mass = 6.98 g/mL * 0.475 mL

Mass = 3.3155 grams

Percent yield = (actual mass / theoretical mass) * 100%

Percent yield = (3.3155 /6.30 ) * 100 %

Percent yield = 52.6 %

3 0

3 years ago

The Society of Automotive Engineers has established an accepted numerical scale to measure the viscosity of motor oil. For examp

natta225 [31]

Answer:

Most viscous to least viscous: $(c)> (b)> (a)$

Explanation:

For hydrocarbons, viscosity increases with increasing molar mass. Because increasing molar mass signifies increase in number of electrons in molecules.

We know that in non-polar hydrocarbons, only van der waal intermolecular force exists. Van der waal force is proportional to number of electrons in a molecule.

Therefore with increasing molar mass, van der waal force increases. hence molecules gets more tightly bind with each other resulting increase in viscosity.

Here molar mass order : $(c)> (b)> (a)$

Therefore viscosity order : $(c)> (b)> (a)$

5 0

3 years ago

Please help.<br><br> Why does the temperature change when a powder is dissolved in water?

Schach [20]

Answer:

In order for the powder to dissolve, each powder molecule must separate from the other powder molecules and be surrounded by water molecules. This shift in arrangement either absorbs or releases energy depending on the situation. It is due to the exchange of energy that the temperature of the solution fluctuates.

Explanation:

:)

5 0

3 years ago

What is the purpose of adding phenolphthalein to your Erlenmeyer flask prior to starting a titration?

koban [17]

Answer:

a. The phenolphthalein acts as a color changing indicator to signal the endpoint of the reaction.

Explanation:

Phenolphthalein is an organic substance with chemical formula $C_{20}H_{14}O_{4}$ .

It is a substance commonly used in acid-base titrations to indicate the end point in the titration because phenolphthalein is colorless in acidic solutions but turns a purplish-pink color in basic solutions.

In this way it helps visually to notice when the final point of the titration has been reached.

3 0

3 years ago