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Serjik [45]
3 years ago
13

Neon lamps, is composed of 90.483% of 20ne, 0.271% of 21ne, and 9.253% of 22ne. the 20ne atoms have a mass of 19.992 u, 21ne ato

ms have a mass of 20.994 u, and those of 22ne have a mass of 21.991 u. calculate the average atomic mass of neon.
Chemistry
1 answer:
WITCHER [35]3 years ago
8 0

20.181 u

The average atomic mass of Ne is the <em>weighted average</em> of the atomic masses of its isotopes.

We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its % abundance).

Thus,  

Avg. at. mass

= (0.904 83× 19.992 u) + (0.002 71 × 20.994) + (0.092 53× 21.991 u)

= 18.0894 u + 0.0569 u  + 2.0348 u = 20.181 u

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The smallest unit of a substance that behaves like the substance is
Reika [66]

Answer : The smallest unit of a substance that behaves like the substance is, molecule.

Explanation :

Pure substance : It is defined as a substance that is made by the combination of only one type of atom or only one type of molecule.

Compound : It is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.

Element : It is a pure substance which is composed of atoms of similar elements.

Molecule : It is the smallest particle in the chemical compound or chemical element or a substance that has the same chemical properties of that compound or element.

Hence, the smallest unit of a substance that behaves like the substance is, molecule.

4 0
3 years ago
The bottom number on the periodic table is called?
salantis [7]

Answer:

The atomic number that should be here, 57, is located at the bottom of the table in the row called the Lanthanides. Directly below the space in Row 6, in Row 7, is another empty space, which is filled by a row called the Actinides, also seen at the bottom of the chart.

Explanation:

hope this helps!

8 0
3 years ago
One application of Hess's Law (which works for ΔH, ΔS, and ΔG) is calculating the overall energy of a reaction using standard en
VikaD [51]

Answer:

The standard change in free energy for the reaction =  - 437.5 kj/mole

Explanation:

The standard change in free energy for the reaction:

                              4 KClO₃ (s) → 3 KClO₄(s) + KCl(s)

Given that   ΔGf(KClO3(s)) = -290.9 kJ/mol;

                    ΔGf(KClO4(s)) = -300.4 kJ/mol;

                    ΔGf(KCl(s)) = -409 kJ/mol

According to Hess's law

ΔGr (Free energy change of reaction)= ∑(Product free energy - reactant free energy)

               ⇒ ΔGr⁰ = {3 x (-300.4) + (-409)} - {3 x (- 290.9)}

                            = - 901.2 - 409 + 872.7

                            =  - 437.5 kj/mole

3 0
3 years ago
During the combustion of a peanut that weighed 0.341 g, the temperature of the 100 mL of water in the calorimeter rose from 23.4
blondinia [14]

Answer:

119 kCal per serving.

Explanation:

The heat energy necessary to elevates water's temperature from 23.4°C to 37.9°C can be calculated by the equation below:

Q = mcΔT

Q: heat energy

m: mass in g

c: specific heat capacity in cal/g°C

ΔT = temperature variation in °C

m is the mass of water, considering the density of water to be 1g/mL, 100 mL of water weights  100g. Therefore:

Q = 100 g x 1.00 cal/g°C x (37.9 - 23.4)°C

Q = 1450 cal

1450 cal ____ 0.341 g peanuts

x             ____  28 g peanuts

x = 119061.58 cal

This means that the cal from fat per serving of peanuts is at least 119 kCal.

3 0
3 years ago
True or false. a wheel and axle are a rotating lever that move around an effort arm?
adelina 88 [10]

Answer:

True

Explanation:

the machine shown in figure 9.9 is called a wheele and axle. It's a form of lever. the effort arm can rotate in a complete circle, which is the center of the axle.

7 0
3 years ago
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