Which has a triangular fiber? Wool Silk Cotton Nylon

David kept 100 grams of radioactive sodium in a container. He observed the amount of sodium left in the container after regular

Anna [14]

First we have to understand what a half life is. A half life is a measure of time when the amount of a certain object is 50% of the original amount. Hence the answer for this is letter A. The initial amount is 100. fifty percent of 100 is 50 and that happens after 15 hours. Hence, 15 hours is the half life period.

5 0

3 years ago

Read 2 more answers

Mercury can be obtained by reacting mercury(I) sulfide with calcium oxide. How many grams of calcium oxide are needed to produce

OLga [1]

First, 55 g of Hg is 3.65 moles because one mole of Hg has a molar mass of 200.59

Then, the mole ratio of Hg to CaO is 8:4 or 2:1. SO we divide 3.65 by 2 to get 1.82 moles of CaO

This is the same as 102.06 grams because one mole of CaO has a molar mass of 56.0774

Hope this helps!

4 0

3 years ago

Sodium chloride procedure

MAVERICK [17]

Answer: Dissolve approximately 3 mg of Sodium Chloride in 2 mL of water.

Add 0.4 mL of silver nitrate TS and acidify with diluted nitric acid.

8 0

2 years ago

Zinc has an average atomic mass of 65.37 amu. Jack is trying to figure out what the most abundant isotope of zinc is, but he doe

Mekhanik [1.2K]

Zinc's most abundant isotope : Zinc-65

<h3>Further explanation </h3>

Isotopes are atoms whose no-atom has the same number of protons while still having a different number of neutrons.

So Isotopes are elements that have the same Atomic Number (Proton)

Atomic mass is the average atomic mass of all its isotopes

In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu

Mass atom X = mass isotope 1 . % + mass isotope 2.%

To decide zinc's most abundant isotope, then choose the closest mass number

or we can check the difference with the average mass number, if the value is the smallest, then that isotope has the largest abundant

Zinc-64

$\tt \dfrac{65.37-64}{65.37}=0.021$

Zinc-65

$\tt \dfrac{65.37-65}{65.37}=0.005$

Zinc-68

$\tt \dfrac{68-65.37}{65.37}=0.04$

Zinc-66

$\tt \dfrac{66-65.37}{65.37}=0.009$

The closest = Zinc-65(the smallest)

5 0

4 years ago

During a laboratory experiment, a 2.36-gram sample of NaHCO3 was thermally decomposed. In this experiment, carbon dioxide and wa

eduard

Answer:

90.7 %

Explanation:

1) Chemical equation (given)

2NaHCO₃ → Na₂CO₃ + H₂CO₃

2) Theoretical yield

a) Convert mass of NaHCO₃ to moles:

n = mass in grams / molar mass
molar mass = 84.007 g/mol
n = 2.36 g / 84.007 g/mol = 0.02809 mol

b) Mole ratio:

2 mol NaHCO₃ : 1 mol H₂CO₃

c) Proportionality:

2 mol NaHCO₃ / mol H₂CO₃ = 0.02809 mol NaHCO₃ / x

⇒ x = 0.2809 / 2 mol H₂CO₃ = 0.01405 mol H₂CO₃

3) Actual yield

a) Mass balance: 2.36 g - 1.57 g = 0.79 g

b) Convert 0.79 g of carbonic acid to number of moles:

n = mass in grams / molar mass

molar mass = 62.03 g/mol

n = 0.79 g / 62.03 g/mol = 0.01274 mol

4) Percentage yield, y (%)

y (%) = actual yield / theoretical yield × 100

y (%) = 0.1274 mol / 0.1405 mol × 100 = 90.68%

The answer must show 3 significant figures, so y(%) = 90.7%.

5 0

3 years ago