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3 years ago

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Gallium has two naturally occurring isotopes. 69Ga (68.9257 amu) is the more abundant isotope, at 60.400%. If the atomic mass of

gallium is 69.723 amu, what is the mass of the other isotope, 71Ga

1 answer:

LiRa [457]3 years ago

8 0

Answer:

70.9391 amu

Explanation:

The abundance of the second isotope is 100 - 60.4% = 39.6%.

We can solve this problem by keeping in mind the <em>following formula for atomic mass</em>:

Atomic mass = Mass of Isotope 1 * Abundance + Mass of Isotope 2 * Abundance

We<u> input the given data</u>:

69.723 = 68.9257 * 60.4/100 + Mass of Isotope 2 * 39.6/100

Mass of Isotope 2 = 70.9391 amu

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MariettaO [177]

I also think it’s B but not quite sure

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3 years ago

How long does it take to electroplate 0.5 mm of gold on an object with a surface area of 31 cm^^ from an Au3+(aq) solution with

konstantin123 [22]

Answer:

It will take 5492 seconds to electroplate 0.5 mm of gold on an object .

Explanation:

Mass of gold = m

Volume of gold = v

Surface area on which gold is plated = $a=31 cm^2$

Thickness of the gold plating = h = 0.5 mm = 0.05 cm

1 mm = 0.1 cm

$V=a\times h=31 cm^2\times 0.05 cm=1.55 cm^3$

Density of the gold = $d=19.3 g/cm^3$

$m=d\times v=19.3 g/cm^3\times 1.55 cm^3=29.915g$

Moles of gold = $\frac{29.915 g}{197 g/mol}=0.152 mol$

$Au^{3+}+3e^-\rightarrow Au$

According to reaction, 1 mole of gold required 3 moles of electrons,then 0.152 moles of gold will require :

$\frac{3}{1}\times 0.152 mol=0.456 mol$ of electrons

Number of electrons = N = $0.456\times \times 6.022\times 10^{23}$

Charge on single electron = $q=1.6\times 10^{-19} C$

Total charge required = Q

$Q=N\times q$

Amount of current passes = I = 8 Ampere

Duration of time = T

$I=\frac{Q}{T}$

$T=\frac{N\times q}{I}$

$=\frac{0.456\times \times 6.022\times 10^{23}\times 1.6\times 10^{-19} C}{8 A}=5492 s$

It will take 5492 seconds to electroplate 0.5 mm of gold on an object .

7 0

3 years ago

By definition 12 grams of carbon-12 must contain how many atoms?

krek1111 [17]

It is defined as the amount of a substance that contains as many particles as there are atoms in 12 grams of pure carbon-12. So, 1 molecule contains 6.022×10^23 elementary entities of the substance.

Hope that helps

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3 years ago

La etiqueta de una bebida transparente con un ligero toque anaranjado indica que contiene aga con un 15 porciento de zumo de nar

Brilliant_brown [7]

<u>Respuesta:</u>

16 gramos de vitamina C y 8 gramos de colorantes.

Explanation:

Debemos multiplicar el porcentaje de cada componente por la cantidad total (100 %) de zumo.

800 g de zumo = 100%

- Tenemos un 2 porciento (2 en 100 o 2/100) de vitamina C. Por lo tanto, la cantidad en gramos de vitamina C es:

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6 0

3 years ago

When a mercury-202 nucleus is bombarded with a neutron, a proton is ejected. What element is formed?

Galina-37 [17]

That will make a gold-202 nucleus.

<h3>Explanation</h3>

Refer to a periodic table. The atomic number of mercury Hg is 80.

Step One: Bombard the $\displaystyle ^{202}_{\phantom{2}80}\text{Hg}$ with a neutron $^{1}_{0}n$ . The neutron will add 1 to the mass number 202 of $^{202}_{\phantom{2}80}\text{Hg}$ . However, the atomic number will stay the same.

New mass number: 202 + 1 = 203.
Atomic number is still 80.

$^{202}_{\phantom{2}80}\text{Hg} + ^{1}_{0}n \to ^{203}_{\phantom{2}80}\text{Hg}$ .

Double check the equation:

Sum of mass number on the left-hand side = 202 + 1 = 203 = Sum of mass number on the right-hand side.
Sum of atomic number on the left-hand side = 80 = Sum of atomic number on the right-hand side.

Step Two: The $^{203}_{\phantom{2}80}\text{Hg}$ nucleus loses a proton $^{1}_{1}p$ . Both the mass number 203 and the atomic number will decrease by 1.

New mass number: 203 - 1 = 202.
New atomic number: 80 - 1 = 79.

Refer to a periodic table. What's the element with atomic number 79? Gold Au.

$^{203}_{\phantom{2}80}\text{Hg} \to ^{202}_{\phantom{2}79}\text{Au} + ^{1}_{1}p$ .

Double check the equation:

Sum of mass number on the left-hand side = 203 = 202 + 1 = Sum of mass number on the right-hand side.
Sum of atomic number on the left-hand side = 80 = 79 + 1 = Sum of atomic number on the right-hand side.

A gold-202 nucleus is formed.

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3 years ago