Answer:
The empirical formula for the compound is Na2O
Explanation:
Data obtained from the question include:
Sodium (Na) = 74.2g
Oxygen (O) = 25.8g
We can obtain the empirical formula for the compound as follow:
First, divide the above by their individual molar mass as shown below:
Na = 74.2/23 = 3.226
O = 25.8/16 = 1.613
Next, divide the above by the smallest number
Na = 3.226/1.613 = 2
O = 1.613/1.613 = 1
Therefore, the empirical formula is:
Na2O
Answer:
force = 3000N
mass= 20 kg
now
F= ma
3000= 20×a
3000÷20=a
a=15
F= ma by newtons second law of motion
Answer:
2.03 moles of Gold
Explanation:
Gold is one of the most precious metal metal used in many applications and mainly as a jewellery. In terms of purity it is categorized in Karats. 24 Karat is considered the purest Gold (i.e. 100 % Gold) while other Karats (14, 18, 22 e.t.c) are alloys with other metals and gyms.
Data Given:
Mass of Gold = 400 g
A.Mass of Gold = 196.97 g.mol⁻¹
Calculate Moles of Gold as,
Moles = Mass ÷ M.Mass
Putting values,
Moles = 400 g ÷ 196.97 g.mol⁻¹
Moles = 2.03 moles of Gold
The elements in the periodice table are not listed in alphabetical order, because the arragement in rows (periods) and columns (groups or familes), in increasing order of atomic number (number of protons of the atoms) permits to explain similarities among the elements, trend in some properties, and even predict properties of unknown elements.
For example, the elements of the first group (family), called alkaline metals, all have 1 valence electron, have similar physical properties (ductibility, malleability, luster, thermal and electricity conductivity), react in similar way with water, show a trend in the atomic radii and in the ionization energy.
You can tell similar stories for other groups like, alkalyne earth metals, halogens and noble gases.
You can also tell trends in electroneativities, and atomic radii, for a row of elements, as per the order they are in the row.
So, the current array resulted very helpul for chemists to explain and predict the behavior and properties of the elements.
