Answer:
To determine a molecular formula from the empirical formula you need to know:
-the molecular mass
-calculate the empirical formula mass
-divide the molecular formular by the empirical formula mass
-multiply by this whole number the empirical formula
Explanation:
See the image below
Answer:
- The molarity of the student's sodium hydroxide solution is 0.0219 M
Explanation:
<u>1) Chemical reaction.</u>
a) Kind of reaction: neutralization
b) General form: acid + base → salt + water
c) Word equation:
- sodium hydroxide + oxalic acid → sodium oxalate + water
d) Chemical equation:
- NaOH + H₂C₂O₄ → Na₂C₂O₄ + H₂O
b) Balanced chemical equation:
- 2NaOH + H₂C₂O₄ → Na₂C₂O₄ + 2H₂O
<u>2) Mole ratio</u>
- 2mol Na OH : 1 mol H₂C₂O₄ :1 mol Na₂C₂O₄ : 2 mol H₂O
<u>3) Starting amount of oxalic acid</u>
- mass = 28 mg = 0.028 g
- molar mass = 90.03 g/mol
- Convert mass in grams to number of moles, n:
n = mass in grams / molar mass = 0.028 g / 90.03 g/mol = 0.000311 mol
<u>4) Titration</u>
- Volume of base: 28.4 mL = 0.0248 liter
- Concentration of base: x (unknwon)
- Number of moles of acid: 2.52 mol (calculated above)
- Proportion using the theoretical mole ratio (2mol Na OH : 1 mol H₂C₂O₄)
That means that there are 0.000622 moles of NaOH (solute)
<u>5) Molarity of NaOH solution</u>
- M = n / V (liter) = 0.000622 mol / 0.0284 liter = 0.0219 M
That is the correct number using <em>three signficant figures</em>, such as the starting data are reported.
Explanation:
Mass ratio C : H : N = 27.3 : 9.10 : 63.6
Mole ratio C : H : N = 27.3/12: 9.10/1 : 63.6/14
( Divide the mass ratio by their molar masses to find the ratio between moles)
Mole ratio = 2.275 : 9.10 : 4.54
= 2.275/2.275 : 9.10/2.275 : 4.54/2.275
= 1 : 4 : 2
Answer is CH4N2
Answer:
potassium I believe is the correct answer
Explanation:
Potassium is the period four element with the lowest mass; its average mass is 39.0983amu.
Answer:
Dalton's atomic theory states that atoms are indivisible. This has been proven through observation to be false: atoms can be divided into protons, neutrons and electrons. Dalton's theory also states that all atoms of an element are identical. This is also false because we know isotopes exist, and while they are still of the same element, they have different numbers of neutrons in their atomic nucleus.
It must have 12 electrons. The negative charge must equal a positive charge since the element has not been specified to be an ion. The reason atomic masses are usually decimal numbers is because electrons actually do contribute to the mass except in a very small amount. That amount is reflected by the decimal numbers you'll see in the atomic mass of an element.
I hope this helps!
