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astra-53 [7]
3 years ago
4

The astronaut then measures the abundance of strontium on the new planet, obtaining the following results: Isotope Abundance (%)

Mass (amu) 86Sr 9.46 85.91 87Sr 7.00 86.91 88Sr 83.54 87.91 What is the atomic mass of strontium for this planet? Express your answer to two decimal places, and include the appropriate units.
Chemistry
1 answer:
lesya692 [45]3 years ago
8 0
The process for knowing all of the aboce is the following:
<span>Atomic mass = (0.0946x85.91) + (0.07x86.91) + (0.8354x87.91) = 87.6508 amu
</span>The answer is that having in mind that Atomic mass is equal to the average number allowing for the relative abundances of different isotopes. That is calaculated by using the following principle or formula:  ΣzₓAₓ 
zₓ is the relative abundance of the isotope and Aₓ is the atomic mass of the isotope.
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Cacodyl, which has an intolerable garlicky odor and is used in the manufacture of cacodylic acid, a cotton herbicide, has a mass
Papessa [141]

Answer:

The molecular formula of cacodyl is C₄H₁₂As₂.

Explanation:

<u>Let's assume we have 1 mol of cacodyl</u>, in that case we'd have 209.96 g of cacodyl and the<u> following masses of its components</u>:

  • 209.96 g * 22.88/100 = 48.04 g C
  • 209.96 g * 5.76/100 = 12.09 g H
  • 209.96 g * 71.36/100 = 149.83 g As

Now we convert those masses into moles:

  • 48.04 g C ÷ 12 g/mol = 4.00 mol C
  • 12.09 g H ÷ 1 g/mol = 12.09 mol H
  • 149.83 g As ÷ 74.92 g/mol = 2.00 mol As

Those amounts of moles represent the amount of each component in 1 mol of cacodyl, thus, the molecular formula of cacodyl is C₄H₁₂As₂.

3 0
2 years ago
Hydrogen, a potential future fuel, can be produced from carbon (from coal) and steam by the following reaction: C(s)+2H2O(g)→2H2
madam [21]

The question is incomplete , complete question is:

Hydrogen, a potential future fuel, can be produced from carbon (from coal) and steam by the following reaction:

C(s)+ 2 H_2O(g)\rightarrow 2H_2(g)+CO_2(g).\Delta H=?

Note that the average bond energy for the breaking of a bond in CO2 is 799 kJ/mol. Use average bond energies to calculate ΔH of reaction for this reaction.

Answer:

The ΔH of the reaction is -626 kJ/mol.

Explanation:

C(s)+ 2 H_2O(g)\rightarrow 2H_2(g)+CO_2(g).\Delta H=?

We are given with:

\Delta H_{H-O}=459 kJ/mol

\Delta H_{H-H}=432 kJ/mol

\Delta H_{C=O}=799 kJ/mol

ΔH =  (Energies required to break bonds on reactant side) - (Energies released on formation of bonds on product side)

\Delta H=(4\times \Delta H_{O-H})-(2\times \Delta H_{H-H}+2\times\Delta H_{C=O})

=(4\times 459 kJ/mol)-(2\times 432 kJ/mol+2\times 799 kJ/mol

\Delta H=-626 kJ/mol

The ΔH of the reaction is -626 kJ/mol.

5 0
2 years ago
A 0.529-g sample of gas occupies 125 ml at 60. cm of hg and 25°c. what is the molar mass of the gas?
Llana [10]

<span>Let's </span>assume that the gas has ideal gas behavior. <span>
Then we can use ideal gas formula,
PV = nRT<span>

</span><span>Where, P is the pressure of the gas (Pa), V is the volume of the gas (m³), n is the number of moles of gas (mol), R is the universal gas constant ( 8.314 J mol</span></span>⁻¹ K⁻¹) and T is temperature in Kelvin.<span>
<span>
</span>P = 60 cm Hg = 79993.4 Pa
V = </span>125  mL = 125 x 10⁻⁶ m³

n = ?

<span> R = 8.314 J mol</span>⁻¹ K⁻¹<span>
T = 25 °C = 298 K
<span>
By substitution,
</span></span>79993.4 Pa<span> x </span>125 x 10⁻⁶ m³ = n x 8.314 J mol⁻¹ K⁻¹ x 298 K<span>
                                          n = 4.0359 x 10</span>⁻³ mol

<span>
Hence, moles of the gas</span> = 4.0359 x 10⁻³ mol<span>

Moles = mass / molar mass

</span>Mass of the gas  = 0.529 g 

<span>Molar mass of the gas</span> = mass / number of moles<span>
                                    = </span>0.529 g / 4.0359 x 10⁻³ mol<span>
<span>                                    = </span>131.07 g mol</span>⁻¹<span>

Hence, the molar mass of the given gas is </span>131.07 g mol⁻¹

4 0
2 years ago
Which of the following type of protons are chemically equivalent? A) homotopic B) enantiotopic C) diastereotopic A &amp; B B &am
Rina8888 [55]

Answer:

A) homotopic and B) enantiotopic

Explanation:

Protons chemically equivalent are those that have the same chemical shift, also if they are interchangeable by some symmetry operation or by a rapid chemical process.

The existence of symmetry axes, Cn, that relate to the protons results in the protons being homotopic, that is chemically equivalent in both chiral and aquiral environments.

The existence of a plane of symmetry, σ, makes the protons related by it, are enantiotopic and these protons will only be equivalent in an aquiral medium; if the medium is chiral both protons will be chemically NOT equivalent. The existence of a center of symmetry, i, in the molecule makes the related protons through it enantiotopic and therefore chemically only in the aquiral medium.

Diastereotopic protons cannot be interconverted by any symmetry operation and they are different, with different chemical displacement.

6 0
2 years ago
help??? Show that you know how to use transitional elements by rewriting the following set of sentences into a coherent paragrap
Darina [25.2K]


Career planning is <span>essential for all high school students. They need to understand their strengths and weaknesses in order to learn where their talents lie. They should know career opportunities for the twenty-first century, their jobs require further schooling and  how much the job they are interested in will pay.</span>
4 0
2 years ago
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