An electron shifts from a lower energy to a higher energy
At the center of every atom lies a small, dense "nucleus" that is positively charged.
Atom is the smallest unit of matter. It is made up of electrons, protons and neutrons. Electrons are negatively charged particles that are found scattered in different energy levels outside the nucleus. Protons are positively charged particles present inside the nucleus. Neutrons do not carry charge and found inside the nucleus. Thus, protons and neutrons make up the nucleus of an atom. Since, protons are positively charged and neutrons are uncharged particles, the charge of nucleus becomes positive.
Answer:
- <em>1.34 × 10²⁴ molecules</em>
Explanation:
To calculate the <em>number of molecules of sodium oxide that will be created if 275 grams of sodium reacts with excess oxygen</em>, use the chemical equation to calculate the number of moles and then multiply by Avogadro's number.
<u>1) Balanced chemical equation (given):</u>
<u>2) Mole ratio:</u>
<u>3) Calculate the number of moles in 275 g of Na:</u>
- n = mass in grams / molar mass
- mass of Na = 275 g
- molar mass of Na₂O = 61.9789 g/mol
- n = 275 g / 61.9789 g/mol = 4.437 mol of Na
<u>4) Set a proportion to find the number of moles of product (Na₂O):</u>
- 2 mol Na₂O / 4 mol Na = x / 4.437 mol Na
- x = 4.437 / 2 mol Na₂O = 2.2185 mol Na₂O
<u>5) Convert the number of moles to number of molecules:</u>
- # molecules = n × 6.022 × 10²³ molecules/mol = 2.2185 mol × 6.022 × 10²³ molecules/mol = 1.34 × 10²⁴ molecules (rounded to 3 significant figures).
Answer:
56 %
Explanation:
The percent dissociation of a weak acid can be defined as:
Moles of weak acid that produced H₃O⁺ species / Total number of weak acid moles * 100%
We are given all the required data to <u>calculate the percent dissociation</u>:
0.42 mol / 0.75 mol * 100 % = 56 %
The percent dissociation is 56%.
