Chemistry, 30.07.2019 01:30 aletadaboss

The astronaut then measures the abundance of magnesium on the new planet, obtaining the following results: isotope abundance (%) mass (amu) 86 sr 9.46 85.91 87 sr 7.00 86.91 88 sr 83.54 87.91 what is the atomic mass of magnesium for this planet? express your answer to two decimal places, and include the appropriate units.

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Answer from: GiaTeyy6536

The average atomic mass of Strontium is 87.65 u

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomcic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

For $_{38}^{86}\textrm{Sr}$ isotope:

Mass of $_{38}^{86}\textrm{Sr}$ isotope = 85.91 u

Percentage abundance of $_{38}^{86}\textrm{Sr}$ isotope = 9.46 %

Fractional abundance of $_{38}^{86}\textrm{Sr}$ isotope = 0.09460

For $_{38}^{87}\textrm{Sr}$ isotope:

Mass of $_{38}^{87}\textrm{Sr}$ isotope = 86.91 u

Percentage abundance of $_{38}^{87}\textrm{Sr}$ isotope = 7.00 %

Fractional abundance of $_{38}^{87}\textrm{Sr}$ isotope = 0.0700

For $_{38}^{88}\textrm{Sr}$ isotope:

Mass of $_{38}^{88}\textrm{Sr}$ isotope = 87.91 u

Percentage abundance of $_{38}^{88}\textrm{Sr}$ isotope = 83.54 %

Fractional abundance of $_{38}^{88}\textrm{Sr}$ isotope = 0.8354

Putting values in equation 1, we get:

$\text{Average atomic mass of Sr}=[(85.91\times 0.0946)+(86.91\times 0.0700)+(87.91\times 0.8354)]$

$\text{Average atomic mass of Sr}=87.65u$

Hence, the average atomic mass of Strontium is 87.65 u

Answer from: Quest

the balanced equation for reaction of ca metal with o2 to produce cao is as below

2 ca+ o2→ 2 cao2

explanation

the reaction is balanced since the number of atoms in reactant side is equal to number of atoms in product side. for example they are 2 atom of ca in reactant side and 2 atoms of ca in the product side.

the process is a meet the requirement of redox reaction because : calcium is oxidized from oxidation state 0 to 2+ while oxygen is reduced from oxidation state 0 to 2-

Answer from: Quest

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally

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