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3 years ago

Which element has the following Electron configuration? *

1 answer:

3 0

Magnesium. You can count the electrons in each level and because the number of electrons is the same with protons you have the atomic number based of which you can get the element in the periodic table

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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

If you burn 46.0 g of hydrogen and produce 411 g of water, how much oxygen reacted?

g100num [7]

The answer is 365 grams because you need to subtract 411 by 46.

3 0

3 years ago

8. If a sample of chloroform is initially at 25°C, what is its final temperature if 150.0 g of chloroform

sashaice [31]

Answer:

The final temperature is 31.95° C.

Explanation:

Given that,

Initial temperature of a sample of chloroform, $T_i=25^{\circ} C$

Mass of chloroform, m = 150 g

It absorbs 1 kJ of heat, Q = 10³ J

The specific heat of chloroform, c = 00.96 J/gºC

We need to find the final temperature. The heat absorbed by an object in terms of specific heat is given by :

$Q=mc\Delta T\\\\Q=mc(T_f-T_i)\\\\\dfrac{Q}{mc}+T_i=T_f\\\\T_f=\dfrac{10^3}{150\times 0.96}+25\\\\=31.95^{\circ} C$

So, the final temperature is 31.95° C.

5 0

3 years ago

By means of a schematic diagram show how a bacteria cell applied to the region of a cowpea root can end up becoming a nitrate io

GenaCL600 [577]

Answer:

Nitrifying Bacteria are a group of aerobic bacteria important in the nitrogen cycle as converters of soil ammonia to nitrates, compounds usable by plants. An example is nitrosomonas or nitrobacter and species in that family.

The schematic diagram is attached below, which summarises the oxidation of ammonia or free nitrogen in the soil to nitrates for the cowpea plant's utilisation.

4 0

3 years ago

An archeologist finds a 1.62 kg goblet that she believes to be made of pure gold. She determines that the volume of the goblet i

maxonik [38]

Density (d) which is the quotient when mass (m) is divided by volume (v) is usually reported in terms of g/mL.
d = m /v
Substituting the known values,
d = (1.62 kg) x (1000 g/ 1 kg) / (205 mL)
The answer would be approximately equal to 7.9 g/mL.

3 0

3 years ago

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