The unbalanced equation is:
Fe(s) + O2(g) —> Fe2O3(s)
To balance oxygens, multiply O2 by 3 and Fe2O3 by 2.
Fe(s) + 3O2(g) —> 2Fe2O3(s)
Balance your iron by multiplying Fe by 4, since you have 4 Fe in the products now.
4Fe(s) + 3O2(g) —> 2Fe2O3(s)
Pretty sure the answer is elements.
Elements are unable to be changed into anything smaller, except through some processes such as particle acceleration, in which case the nucleus is split into either chunks of protons and neutrons or into small pieces of either one.
Answer:
![\boxed{\text{b) 300.0 mL of 0.10 mol/L CaCl}_{2}}](https://tex.z-dn.net/?f=%5Cboxed%7B%5Ctext%7Bb%29%20300.0%20mL%20of%200.10%20mol%2FL%20CaCl%7D_%7B2%7D%7D)
Explanation:
a) 400.0 mL of 0.10 M NaCl
(i) Moles of NaCl
![\text{ Moles of NaCl } = \text{0.4000 L NaCl} \times \dfrac{\text{0.10 mol NaCl}}{\text{1 L NaCl}} = \text{0.040 mol NaCl}](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20NaCl%20%7D%20%3D%20%5Ctext%7B0.4000%20L%20NaCl%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B0.10%20mol%20NaCl%7D%7D%7B%5Ctext%7B1%20L%20NaCl%7D%7D%20%3D%20%5Ctext%7B0.040%20mol%20NaCl%7D)
(ii) Moles of ions
NaCl(s) ⟶ Na⁺(aq) + Cl⁻(aq)
We get 2 mol of ions from 1 mol of NaCl
![\text{Moles of ions } = \text{0.040 mol NaCl} \times \dfrac{\text{2 mol ions}}{\text{1 mol NaCl}} = \text{0.080 mol ions}](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20ions%20%7D%20%3D%20%5Ctext%7B0.040%20mol%20NaCl%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B2%20mol%20ions%7D%7D%7B%5Ctext%7B1%20mol%20NaCl%7D%7D%20%3D%20%5Ctext%7B0.080%20mol%20ions%7D)
b) 300.0 mL of 0.10 M CaCl₂
(i) Moles of CaCl₂
![\text{ Moles of CaCl}_{2} =\text{0.3000 L CaCl}_{2} \times \dfrac{\text{0.10 mol CaCl}_{2}}{\text{1 L CaCl}_{2}} = \text{0.030 mol CaCl}_{2}](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20CaCl%7D_%7B2%7D%20%3D%5Ctext%7B0.3000%20L%20CaCl%7D_%7B2%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B0.10%20mol%20CaCl%7D_%7B2%7D%7D%7B%5Ctext%7B1%20L%20CaCl%7D_%7B2%7D%7D%20%3D%20%5Ctext%7B0.030%20mol%20CaCl%7D_%7B2%7D)
(ii) Moles of ions
CaCl₂(s) ⟶ Ca²⁺(aq) + 2Cl⁻(aq)
We get 3 mol of ions from 1 mol of CaCl₂
![\text{Moles of ions } = \text{0.030 mol CaCl}_{2} \times \dfrac{\text{3 mol ions}}{\text{1 mol CaCl}_{2}} = \text{0.090 mol ions}](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20ions%20%7D%20%3D%20%5Ctext%7B0.030%20mol%20CaCl%7D_%7B2%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B3%20mol%20ions%7D%7D%7B%5Ctext%7B1%20mol%20CaCl%7D_%7B2%7D%7D%20%3D%20%5Ctext%7B0.090%20mol%20ions%7D)
c) 200.0 mL of 0.10 M FeCl₃
(i) Moles of FeCl₃
![\text{ Moles of FeCl}_{3} =\text{0.2000 L FeCl}_{3} \times \dfrac{\text{0.10 mol FeCl}_{3}}{\text{1 L FeCl}_{3}} = \text{0.020 mol FeCl}_{3}](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20FeCl%7D_%7B3%7D%20%3D%5Ctext%7B0.2000%20L%20FeCl%7D_%7B3%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B0.10%20mol%20FeCl%7D_%7B3%7D%7D%7B%5Ctext%7B1%20L%20FeCl%7D_%7B3%7D%7D%20%3D%20%5Ctext%7B0.020%20mol%20FeCl%7D_%7B3%7D)
(ii) Moles of ions
FeCl₂(s) ⟶Fe³⁺(aq) + 3Cl⁻(aq)
We get 4 mol of ions from 1 mol of FeCl₃
![\text{ Moles of FeCl}_{3} =\text{0.2000 L FeCl}_{3} \times \dfrac{\text{0.10 mol FeCl}_{3}}{\text{1 L FeCl}_{3}} = \text{0.020 mol FeCl}_{3}](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20FeCl%7D_%7B3%7D%20%3D%5Ctext%7B0.2000%20L%20FeCl%7D_%7B3%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B0.10%20mol%20FeCl%7D_%7B3%7D%7D%7B%5Ctext%7B1%20L%20FeCl%7D_%7B3%7D%7D%20%3D%20%5Ctext%7B0.020%20mol%20FeCl%7D_%7B3%7D)
d) 200.0 mL of 0.10 M KBr
(i) Moles of KBr
![\text{ Moles of KBr} = \text{0.2000 L KBr} \times \dfrac{\text{0.10 mol KBr }}{\text{1 L KBr}} = \text{0.020 mol KBr}](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20KBr%7D%20%3D%20%5Ctext%7B0.2000%20L%20KBr%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B0.10%20mol%20KBr%20%7D%7D%7B%5Ctext%7B1%20L%20KBr%7D%7D%20%3D%20%5Ctext%7B0.020%20mol%20KBr%7D)
(ii) Moles of ions
KBr(s) ⟶ K⁺(aq) + Br⁻
We get 2 mol of ions from 1 mol of KBr
![\text{Moles of ions } = \text{0.020 mol KBr} \times \dfrac{\text{2 mol ions}}{\text{1 mol KBr}} = \text{0.040 mol ions}\\\\\text{We get the most ions ions from }\boxed{\textbf{300.0 mL of 0.10 mol/L CaCl}_{2}}](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20ions%20%7D%20%3D%20%5Ctext%7B0.020%20mol%20KBr%7D%20%5Ctimes%20%5Cdfrac%7B%5Ctext%7B2%20mol%20ions%7D%7D%7B%5Ctext%7B1%20mol%20KBr%7D%7D%20%3D%20%5Ctext%7B0.040%20mol%20ions%7D%5C%5C%5C%5C%5Ctext%7BWe%20get%20the%20most%20ions%20ions%20from%20%7D%5Cboxed%7B%5Ctextbf%7B300.0%20mL%20of%200.10%20mol%2FL%20CaCl%7D_%7B2%7D%7D)
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