N(CaCO3)=m÷M
m being the mass of the sample and M being the molar mass of the compound; Molar mass is to be obtained by adding the atomic masses of all the elements in the compound.
therefore,
n(CaCO3)=m÷M
=28g÷100 g.mol
=0.28 mol
therefore, there are 0.28 moles in 28g of Calcium Carbonate.
Answer:
<em><u>Question 1.</u></em><em> → </em>The amount remained is 15.625 g after 5 half-lives (30 hours).
<u><em>Question 2. </em></u><em>→ </em>mass % of water =41.4 %
<u><em>Question 3. </em></u><em>→ </em>C. 64 grams.
Explanation:
<em><u>Question 1. </u></em>
It is known that the decay of isotopes and radioactive material obeys first order kinetics.
Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
Thus, 30 hours represent (30/6) 5 half-lives.
500 g →(first 1/2 life) 250 g →(second 1/2 life) 125 g →(third 1/2 life) 62.5 g →(fourth 1/2 life) 31.25 g →(fifth 1/2 life) 15.625 g
So, The amount remained is 15.625 g after 5 half-lives (30 hours).
<u><em>Question 2.</em></u>
- The formula of Copper (II) Fluoride tetra hydrate is CuF₂.4H₂O.
- the molar mass of Copper (II) Fluoride tetra hydrate is the sum of the atomic masses o each element.
- molar mass of 1 mol of CuF₂.4H₂O = 64 + 2*(19) + 8* (1) + 4*(16) = 174 g/mol.
- molar mass of 4 mol of H₂O = 8*(1) + 4*(16) = 72 g/mol
- 1 mol of Copper (II) Fluoride tetra hydrate → 4 mol H₂O
mass % of water = (mass of 4 mol of H₂O) / (mass of 1 mol of CuF₂.4H₂O ) *100 = (72 /174) *100 = 41.4 %
<em><u>Question 3. </u></em>
<u>Mass percentage</u> is defined as the mass of a solute divided by the total mass of the solution, multiplied by 100
- mass percent = ( mass of solute / mass of solution) *100
∴ 16 = ( mass of solute / 400 g) *100
mass of solute = (16* 400)/ 100 = 64 g.
So the right choice is C. 64 grams.
Answer:
Explanation:
According to the law of definite proportions, particles in a compound combine by a defined stoichiometric ratio. This ratio is also calculated in terms of moles.
In order to find the ratio between the particles in a compound, we need to find the molar ratio of each species.
Notice that the ratio between the number of moles of zinc to the number of moles of nitrogen is:
This means if we are given 1 zinc ion, we expect to have a total of 2 nitrogen atoms. Therefore, x = 2.
HCl is more soluble in diethyl ether.
<h3>Reason ; </h3>
H-Cl is a covalent molecule with a dipole-dipole interaction. As a result, diethyl ether may easily replace HCl's dipole-dipole interaction to dissolve it. As a result, HCl dissolves more easily in diethyl ether than NaCl. As a result, HCl(g) dissolves more easily in diethyl ether than NaCl (s).
<h3>What is Covalent molecule ?</h3>
A covalent bond is a chemical relationship that requires the sharing of electrons between atoms to generate electron pairs. These electron pairs are known as shared pairs or bonding pairs, and covalent bonding is the stable equilibrium of attractive and repulsive forces between atoms when they share electrons.
<h3>What is dipole-dipole interaction ?</h3>
Dipole-dipole interactions are weak interactions that occur when permanent or induced dipoles come into close proximity. These forces are referred to collectively as Van der Waals interactions. Proteins have a vast number of these interactions, the strength of which varies greatly.
To know more about Covalent bond please click here ; brainly.com/question/3447218
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Answer:
arsenic
Explanation:helium is a gas and aluminum is a etal and carbon is not a maetalloid