Answer:
Approximately 75%.
Explanation:
Look up the relative atomic mass of Ca on a modern periodic table:
There are one mole of Ca atoms in each mole of CaCO₃ formula unit.
- The mass of one mole of CaCO₃ is the same as the molar mass of this compound:
. - The mass of one mole of Ca atoms is (numerically) the same as the relative atomic mass of this element:
.
Calculate the mass ratio of Ca in a pure sample of CaCO₃:
.
Let the mass of the sample be 100 g. This sample of CaCO₃ contains 30% Ca by mass. In that 100 grams of this sample, there would be
of Ca atoms. Assuming that the impurity does not contain any Ca. In other words, all these Ca atoms belong to CaCO₃. Apply the ratio
:
.
In other words, by these assumptions, 100 grams of this sample would contain 75 grams of CaCO₃. The percentage mass of CaCO₃ in this sample would thus be equal to:
.
Answer:
The process of unstable (or radioactive) atoms becomes stable by emitting radiation. This event over time is called radioactive decay. Alpha decay results in the loss of two protons and two neutrons from the nucleus
Answer:
The incorrect statement is: SO₂ gains electrons
Explanation:
A chemical reaction that involves the simultaneous transfer of electrons between two chemical species, is known as the redox reaction.
Given chemical reaction: 2SO₂(g) + O₂(g) → 2SO₃(g)
In this redox reaction, S is present in +4 oxidation state in SO₂ and +6 oxidation state SO₃. Whereas, O is present in 0 oxidation state in O₂ and -2 oxidation state in SO₃.
<u>Therefore, SO₂ loses electrons and thus gets oxidized. Whereas, O₂ gains electrons and thus gets reduced. </u>
<u>In this reaction, SO₂ is the reducing agent and O₂ is the oxidizing agent.</u>
Answer:
1.57 mol NaN₃
Explanation:
- 2 NaN₃ (s) → 2 Na (s) + 3 N₂ (g)
First we <u>use PV=nRT to calculate the number of N₂ moles that need to be produced</u>:
- R = 0.082 atm·L·mol⁻¹·K⁻¹
- T = 23.7 °C ⇒ 23.7 + 273.16 = 296.86 K
<u>Inputing the data</u>:
- 1.07 atm * 53.4 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 296.86
And <u>solving for n</u>:
Finally we <u>convert N₂ moles into NaN₃ moles</u>, using <em>the stoichiometric coefficients of the balanced reaction</em>:
- 2.35 mol N₂ *
= 1.57 mol NaN₃