Answer:
69.55 (w/w) %
Explanation:
When NaHCO3 reacts with an acid HA, the reaction that occurs is:
NaHCO3 + HA → H2O + NaA + CO2
<em>Where 1 mole of NaHCO3 produce 1 mole of CO2</em>
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Thus, we need to convert the mass of CO2 to moles using its molar mass (44g/mol). Then, based on the chemical equation, moles of CO2 produced are equal to moles of NaHCO3 in the mixture. With its molar mass -84g/mol- we can find the mass of NaHCO3 and mass percent:
<em>Moles CO2:</em>
0.561g * (1mol / 44g) = 0.01275 moles CO2 = Moles NaHCO3.
<em>Mass NaHCO3:</em>
0.01275 moles * (84g/mol) = 1.071g NaHCO3
<em>Mass percent:</em>
1.071g NaHCO3 / 1.54g sample * 100
<h3>69.55 (w/w) %</h3>
Answer: An atomic number of 8
Explanation:
All oxygen atoms have an atomic number of 8 in common, but could differ in mass number in their isotopes.
Examples of oxygen atoms are O16, O17, and O18. They all have an atomic number of 8, but different mass numbers of 16, 17, and 18 respectively. Thus, they are isotopes of oxygen.
Sc (neutral) [Ar] 3d1 4s2
Sc+ [Ar] 3d1 4s1
Sc2+ [Ar] 3d1
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Thus, the fourth level can hold up to 32electrons: 2 in the s orbital, 6 in the three p orbitals, 10 in the five d orbitals, and 14 in the seven f orbitals. The sublevels of the first four principal energy levels and the maximum number of electrons that the sublevels can contain are summarized in Table 5.1.
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