What is the total number of protons in the nucleus of calcium -42?

Which of the following is NOT a variable property for a gas?

Alex_Xolod [135]

Mass, air has that. Since what fills up a balloon? A gas
Shape, it has no definite shape. This one is accurate, it has no definite shape, it takes the shape of the object it's in.
Volume, does air take up space? If it does then yep. Balloon example/
Density, yes it does, because it's tightly wounded up.

D

5 0

3 years ago

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What is the molar ratio for the following equation after it has been properly balanced?

hichkok12 [17]

6 Na + 1 Fe₂O₃ → 3 Na₂O + 6 Fe

<h3>Explanation</h3>

Method One: Refer to electron transfers.

Oxidation states:

Na: from 0 to +1; loses one electron.
Fe: from +3 to 0; gains three electrons.

Each mole of Fe₂O₃ contains two Fe atoms and will gain 2 × 3 = 6 electrons during the reaction. It takes 6 moles of Na to supply all those electrons.

6 Na + 1 Fe₂O₃ → ? Na₂O + ? Fe

There are two moles of Na atoms in each mole of Na₂O. 6 moles of Na will make 3 moles of Na₂O.
There are two moles of Fe atoms in each mole of Fe₂O₃. 1 mole of Fe₂O₃ will make 2 moles of Fe.

6 Na + 1 Fe₂O₃ → 3 Na₂O + 2 Fe

Method Two: Atoms conserve.

Fe₂O₃ has the largest number of atoms among one mole of all four species in this reaction. Assume one as its coefficient.

? Na + 1 Fe₂O₃ → ? Na₂O + ? Fe

There are two moles of Fe atoms and three moles of O atoms in each mol of Fe₂O₃. One mole of Fe₂O₃ contains two moles of Fe and three moles of O. There are one mole of O atom in every mole of Na₂O. Three moles of O will go to three moles of Na₂O.

? Na + 1 Fe₂O₃ → 3 Na₂O + 2 Fe

Each mole of Na₂O contains two moles of Na. Three moles of Na₂O will contain six moles of Na.

6 Na + 1 Fe₂O₃ → 3 Na₂O + 2 Fe

Simplify the coefficients. All coefficients in this equation are now full number and relatively prime. Hence the equation is balanced.

6 Na + 1 Fe₂O₃ → 3 Na₂O + 2 Fe

6 0

3 years ago

How many moles of water are in 1.23x10^18 water molecules

Harlamova29_29 [7]

By 1.23 x 1024 you mean 10 to the power of 24 molecules? If so all you need to do is divide the number of molecules you have by Avagadros number, 6.022 x 10^23. This will give you the mols of water, or the mols of anything, since there is always 6.022 x 10^23 molecules in 1 mol of substance.

1.23x10^24 atoms/6.022x10^23 atom/mol = 2.04 mol H20

6 0

2 years ago

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Which atom in the ground state has the same electron configuration as a calcium ion, Ca2+, in the ground state?(1) Ar(2) K(3) Mg

Irina-Kira [14]

atoms are made of 3 types of subatomic particles; electrons, protons and neutrons

atomic number is the number of protons. atomic number is characteristic for the element. In ground state atoms, the number of electrons and protons are the same.

the electronic configuration of Ca in the ground state is

Ca - 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

when Ca loses its 2 valence electrons, it becomes positively charged and the electronic configuration becomes

Ca - 1s² 2s² 2p⁶ 3s² 3p⁶

number of electrons in Ca²⁺ is 18

the atom in the ground state would have the same number of electrons and protons. Therefore number of protons are 18. then the atomic number of the element is 18

the atom having an atomic number of 18 is Ar.

the answer is 1) Ar

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2 years ago

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Lead(II) oxide from an ore can be reduced to elemental lead by heating in a furnace with carbon. Calculate the expected yield of

Lelu [443]

Answer:

53kg is the expected yield of lead

Explanation:

Firstly, in order to solve this question, we need to write the equation of reaction correctly. This is as follows:

PbO(s) + C(s) ---> Pb(l) + CO(g)

We proceed from here. We should get the limiting reactant but this can only be obtained by getting the number of moles of each reactant present.

The formula to use across all boards is that the number of moles is the mass of each of the reactant divided by the molar mass of each of the reactant.

For PBO, mass is 57kg = 57000g

Molar mass of PBO = 223.20g/mol

The number of moles is thus 57,000/223.2 = 255.37 moles

For carbon, mass is also 57kg = 57000g

Molar mass is 12g/mol

Number of moles of carbon = 57000/12 = 4750 moles

From the number of moles, we can see that the number of moles of Carbon is greater than that of PbO. This means that PbO is the limiting reagent.

Hence we use it to calculate percentage yield.

The number of moles of lead formed is the same of number of moles of lead oxide = 255.37 since we have mole ratio of 1 to 1

The molar mass of lead is 207.20g/mol

The mass of lead formed is = moles of lead formed * molar mass of lead = 207.20 * 255.37 = 52,912g which is approximately 53kg

Hence the expected yield is 53kg

6 0

3 years ago