Answer:
3.43 %
Explanation:
We need to calculate first the number of moles of CeO2 produced in the combustion. Given its formula we know how many moles of Ce atom are present. From there calculate the mass this number of moles this represent and then one can calculate the percentage.
0.1848 g CeO2 x 1 mol CeO2/172.114g = 0.00107 mol CeO2
0.00107 mol CeO2 x 1 mol Ce/ 1 mol CeO2 = 0.00107 mol Ce
.00107 mol Ce x 140.116 g Ce/ mol = 0.150 g Ce
0.150 g Ce/ 4.3718 g sample x 100 = 3.43 %
Answer: c. balance
Explanation: Mass is the amount of matter contained in a body.
14. C
15. B
16. D
17. D
18. I am not sure sorry.<span />
Answer: This chemical reaction is a neutralization reaction between the Milk of Magnesia and the HCl from the stomach. The balanced equation is Mg(OH)2 (s) + 2 HCl (aq) → MgCl2 (aq) + 2 H2O (l)
Explanation:
The reaction between the HCl and the Mg(OH)2 is a neutralizacion reaction , because the HCl is a strong acid and the Mg(OH)2 is a weak base, then both react and the pH of the medium will increase, so the stomach trouble will dissapear.
Mg(OH)2 (s) + 2 HCl (aq) → MgCl2 (aq) + 2 H2O (l)
Magnesium hydroxide is a weak base due to its very limited solubility in water. This property is a great advantage when treating the excess of HCl in the stomach, because the Mg(OH)2 molecule does not dissociated easily until it reacts with the hydrogen ion, H+ of the HCl. So the effect of the Mg(OH)2 will last longer until the annoyance dissapear.
