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3 years ago

What is scientific notation

Chemistry

1 answer:

forsale [732]3 years ago

8 0

scientific notation is a mathematical way to turn large of small numbers into a simpler form.

ex. 9000000000 is 9*10^9 in scientific notation

ex. 0.000000009 is 9*10^-9 in scientific notation

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1.) Rust forms when Fe, O₂, and H₂O react in the balanced equation below;

valentinak56 [21]

Answer:

1.) A.) The limiting reactant is Fe.

B.) 16.17 g.

2.) 84.70 %.

Explanation:

For the balanced equation:

2Fe(s) + O₂(g) + 2H₂O(l) → 2Fe(OH)₂(s).

2.0 moles of Fe reacts with 1.0 mole of oxygen and 2.0 moles of water to produce 2.0 moles of Fe(OH)₂.

A.) Which of these reactants is the limiting reagent?

To determine the limiting reactant, we should calculate the no. of moles of reactants using the relation: n = mass/molar mass.

Suppose that water is exist in excess.

no. of moles Fe = mass/atomic mass = (10.0 g)/(55.845 g/mol) = 0.179 mol ≅ 0.18 mol.

no. of moles of O₂ = mass/molar mass = (4.0 g)/(32.0 g/mol) = 0.125 mol.

Since from the balanced equation; every 2.0 moles of Fe reacts with 1.0 mole of oxygen.

So, 0.18 mol of Fe reacts with 0.09 mol of O₂.

Thus, the limiting reactant is Fe.

The reactant in excess is O₂ (0.125 mol - 0.09 mol = 0.035 mol).

B.) How many grams of Fe(OH)₂ are formed?

Using cross multiplication:

∵ 2.0 moles of Fe produce → 2.0 moles of Fe(OH)₂.

∴ 0.18 moles of Fe produce → 0.18 moles of Fe(OH)₂.

∴ The mass (no. of grams) of produced 0.18 mol of Fe(OH)₂ = no. of moles x molar mass = (0.18 mol)(89.86 g/mol) = 16.17 g.

2.) (Using the reaction listed in question 1.) If 2.00 g Fe is reacted with an excess of O₂ and H₂0, and a total of 2.74 g of Fe(OH)₂ is actually obtained, what is the % yield?

The % yield = [(actual mass/calculated mass)] x 100.

The actual mass = 2.74 g.

We need to calculate the theoretical mass:

Firstly, we should calculate the no. of moles of reactants using the relation: n = mass/molar mass.

no. of moles Fe = mass/atomic mass = (2.0 g)/(55.845 g/mol) = 0.0358 mol ≅ 0.036 mol.

Using cross multiplication:

∵ 2.0 moles of Fe produce → 2.0 moles of Fe(OH)₂.

∴ 0.036 moles of Fe produce → 0.036 moles of Fe(OH)₂.

∴ The calculated mass (no. of grams) of produced 0.036 mol of Fe(OH)₂ = no. of moles x molar mass = (0.036 mol)(89.86 g/mol) = 3.235 g.

∴ The % yield = [(actual mass/calculated mass)] x 100 = [(2.74 g/3.235 g)] x 100 = 84.70 %.

4 0

4 years ago

When we looked at assigning the electrons in nitrogen to sites in the 2s and 2p orbitals, we used the 2s anti-bonding site. Whic

AveGali [126]

Answer:

B) Although this site is not desirable for making a bond between atoms, it is a good site in the sense that the electrons can be close to the nucleus.

Explanation:

An antibonding orbital points away from the nuclei, with a node between them, so the electrons are not held close to the nuclei. The orbital is not desirable for bonding.

The diagram below shows a σ*1s molecular orbital, but a σ*2s orbital has a similar shape.

A) is true. The σ*1s orbital has the lowest energy.

C) is true. Any orbital can accommodate at most one electron pair.

D) is may be true. Orbital energy decreases as atomic number increases, so the orbital energy of an N₂ σ*2s molecule may be close to that of a sulfur atom's 2s orbital.