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3 years ago

If you have 0.50 mol of ca, how many atoms are present?

1 answer:

6 0

Answer is: there are 3.011·10²³ atoms of calcium.

n(Ca) = 0.50 mol; amount of substance(calcium).
Na = 6.022·10²³ 1/mol; Avogadro's constant or number.
N(Ca) = n(Ca) · Na.
N(Ca) = 0.50 mol · 6.022·10²³ 1/mol.
N(Ca) = 3.011·10²³; number of calcium atoms.
The mole is an SI unit which measures the number of particles in substance. One mole is equal to 6.022·10²³ atoms.

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A solution in a dish contains 4.0 grams of salt dissolved in 100 grams of water. If 50 grams of the water evaporates, this is ev

MaRussiya [10]

D. A mixture

If the water is evaporating while the salt remains, it means the two are not chemically bonded and therefore are not a compound.

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3 years ago

Which statement describes how chemical formula such as H20 represent compounds check all that apply

Allisa [31]

<h3>Answer:</h3>

They show the elements of make up a compound
They show the types of atoms that make up a molecule
They show the number of each type of atom in a molecule

<h3>Explanation:</h3>

To answer this question we need to know what is a compound.

A compound is a substance that is made by two or more atoms of different elements that are chemically combined.
A chemical formula of a compound is a formula that shows the elements that make up a compound and also the types of atoms that make up the molecule.
Additionally, the chemical formula shows the number of each type of atom in a molecule.
In this case, the chemical formula of a molecule of H₂O shows that it is made up of one hydrogen atom and two oxygen atoms.

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3 years ago

Chlorine has two naturally occurring isotopes, 35C1 Gsotopic mass 34.9689 amu) and 370 (isotopic mass 36.9659 amu). If chlorine

Lilit [14]

Answer: The percentage abundance of $_{17}^{35}\textrm{Cl}$ and $_{17}^{37}\textrm{Cl}$ isotopes are 75.77% and 24.23% respectively.

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:

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

Let the fractional abundance of $_{17}^{35}\textrm{Cl}$ isotope be 'x'. So, fractional abundance of $_{17}^{37}\textrm{Cl}$ isotope will be '1 - x'

For $_{17}^{35}\textrm{Cl}$ isotope:

Mass of $_{17}^{35}\textrm{Cl}$ isotope = 34.9689 amu

Fractional abundance of $_{17}^{35}\textrm{Cl}$ isotope = x

For $_{17}^{37}\textrm{Cl}$ isotope:

Mass of $_{17}^{37}\textrm{Cl}$ isotope = 36.9659 amu

Fractional abundance of $_{17}^{37}\textrm{Cl}$ isotope = 1 - x

Average atomic mass of chlorine = 35.4527 amu

Putting values in equation 1, we get:

$35.4527=[(34.9689\times x)+(36.9659\times (1-x))]\\\\x=0.7577$

Percentage abundance of $_{17}^{35}\textrm{Cl}$ isotope = $0.7577\times 100=75.77\%$

Percentage abundance of $_{17}^{37}\textrm{Cl}$ isotope = $(1-0.7577)=0.2423\times 100=24.23\%$

Hence, the percentage abundance of $_{17}^{35}\textrm{Cl}$ and $_{17}^{37}\textrm{Cl}$ isotopes are 75.77% and 24.23% respectively.

6 0

3 years ago

Which structure is unique to vertebrates? limbs brain skin backbone

IRISSAK [1]

Answer:

Backbone

Explanation:

Organisms that have backbones are known as vertebrates, while the ones without a backbone are classified as invertebrates.

4 0

3 years ago

If 2.00 g of mg reacts completely with 50.0 ml of hcl solution, what is the molarity of the hcl solution? mg(s) + 2hcl(aq) → mgc

Amanda [17]

The molarity of HCl is calculated as below

find the moles of mg used
moles = mass /molar mass

= 2.00g/24 g/mol=0.083 moles
write the reacting equation
Mg(s) +2HCl (aq)= MgCl2(aq) + H2(g)

by use of mole ratio between Mg to HCl which is 1 :2 the moles of HCl is therefore
= 0.083 x2 =0.166 moles

molarity of HCl = moles of HCl/ volume in dm^3

that is 0.166/50 x1000= 3.3 M of HCl

6 0

3 years ago

Read 2 more answers