Answer:
0.234 moles
Explanation:
moles of Al2O3 = mass / molar mass
moles of Al2O3 = 23.87g / 102.0g/mol
moles of Al2O3 = 0.234 moles (to three significant figures)
The concentration of the hydronium ion in hydrochloric acid is 0.0045 M, and the pH of the solution is 2.34.
<h3>What is pH?</h3>
pH is the potential of the hydrogen or the hydronium ions in the aqueous solution.
As the solution contains 
HCl the concentration of the hydronium ion will be the same, 
The pH of the solution is calculated as:
![\begin{aligned} \rm pH &= \rm -log[H^{+}]\\\\&= - \rm log (4.5 \times 10^{-3})\\\\&= 2.34\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Crm%20pH%20%26%3D%20%5Crm%20-log%5BH%5E%7B%2B%7D%5D%5C%5C%5C%5C%26%3D%20-%20%5Crm%20log%20%284.5%20%5Ctimes%2010%5E%7B-3%7D%29%5C%5C%5C%5C%26%3D%202.34%5Cend%7Baligned%7D)
The concentration of the hydroxide ion is calculated from pH and hydronium ion as:
![\begin{aligned} \rm [H_{3}O^{+}][OH^{-}] &= 10^{-14}\\\\&= \dfrac{1 \times 10^{-14}}{4.5 \times 10^{-3}}\\\\&= 2.2 \times 10^{12}\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Crm%20%5BH_%7B3%7DO%5E%7B%2B%7D%5D%5BOH%5E%7B-%7D%5D%20%26%3D%2010%5E%7B-14%7D%5C%5C%5C%5C%26%3D%20%5Cdfrac%7B1%20%5Ctimes%2010%5E%7B-14%7D%7D%7B4.5%20%5Ctimes%2010%5E%7B-3%7D%7D%5C%5C%5C%5C%26%3D%202.2%20%5Ctimes%2010%5E%7B12%7D%5Cend%7Baligned%7D)
Now, for the calcium hydroxide solution, the calculations are shown as,
pOH is calculated as:
![\begin{aligned} \rm pOH &= 14- 8 = 6\\\\\rm [OH^{-}] &= \rm antilog (-6)\\\\&= 10^{-6} \end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Crm%20pOH%20%26%3D%2014-%208%20%3D%206%5C%5C%5C%5C%5Crm%20%5BOH%5E%7B-%7D%5D%20%26%3D%20%20%5Crm%20antilog%20%28-6%29%5C%5C%5C%5C%26%3D%2010%5E%7B-6%7D%20%5Cend%7Baligned%7D)
The concentration of calcium hydroxide is calculated as:
![\begin{aligned} &= \dfrac{1}{2} \times \rm [OH^{-}]\\\\&= 5 \times 10^{-4} \;\rm M\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%26%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%5Ctimes%20%5Crm%20%5BOH%5E%7B-%7D%5D%5C%5C%5C%5C%26%3D%205%20%5Ctimes%2010%5E%7B-4%7D%20%5C%3B%5Crm%20M%5Cend%7Baligned%7D)
Therefore, the pH and the pOH give the concentration of the hydrogen or the hydronium ion and the hydroxide ion.
Learn more about pH and pOH here:
brainly.com/question/16062632
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For combustion reaction we need oxygen and the results most of the time produce heat which mean first one is correct.
Answer:
Hope this helps
Explanation:
A generalization I can make about the Huang River is that the Huang River is the most important river in China. Also called the Yellow River, it is where historians believe ancient Chinese people settle in to develop its civilization on the banks of the river for the many benefits it had for life and agriculture. However, early Chinese people had to learn how to control the floods of the river in order to survive ad prosper.
Answer:
hope this helps <3
Explanation:
Landon glances across the dinner table and thinks to himself that his fathers curly hair looks just like his own. He wishes his hair were straight like his mothers because he thinks he looks better with straight hair. Landon works hard to keep it straighter by combing and using hair gel, but it usually curls right back up. He has his mothers nose, but not her hair, unlike his sister Emily, who is also the result of the combination of the DNA from both of his parents and has straight hair like their mothers. Most eukaryotic organisms, like Landon, are formed through the process of sexual reproduction. Landon realizes that he and Emily are evidence that sexual reproduction, the combination of their two parents, creates diverse offspring.
Landons dinner plate is filled with one of his favorite foods-mashed potatoes made from potatoes fresh from his grandmothers garden. He remembers helping her get ready to plant the potatoes in early spring. They cut each potato into several pieces and planted the pieces in a nice straight row in the garden. When these eukaryotic plants came up, he noticed that each plant looked like all the others. These identical offspring with uniform traits are the result of asexual reproduction. Landons grandmother grew potatoes by cutting the whole potato into smaller pieces, which is a type of asexual reproduction called vegetative propagation.
After dinner, Landon wanted to go watch television, but his mother insisted that he put the leftover food in the refrigerator. Perhaps she knew that the cool temperature inside the refrigerator would stop the growth of bacteria, which are prokaryotic and can reproduce asexually in as little as 20 minutes. This rapid asexual reproduction, called binary fission, would produce thousands and thousands of identical bacterial cells that could cause Landons tasty leftover food to spoil before the end of his favorite show.
Landon finishes up the dishes and puts away the leftovers. As he sets the last dinner glass back into the cupboard, he catches a glimpse of his curly hair in his reflection. He thinks to himself that his mothers nose and his fathers hair are actually a good combination that looks pretty good on him
