Answer:
Mass = 8 g
Explanation:
Given data:
Mass of MgO formed = 20 g
Mass of oxygen needed = ?
Solution:
Chemical equation:
2Mg + O₂ → 2MgO
Number of moles of MgO:
Number of moles = mass/molar mass
Number of moles = 20 g/ 40 g/mol
Number of moles = 0.5 mol
Now we will compare the moles of MgO and O₂ from balance chemical equation:
MgO : O₂
2 : 1
0.5 : 1/2×0.5 = 0.25 mol
Mass of oxygen required:
Mass = number of moles × molar mass
Molar mass of O₂ is 32 g/mol
Mass = 0.25 mol × 32 g/mol
Mass = 8 g
Answer:
no
Explanation:
Fe (iron) <u>loses</u> three electrons.The ionic bond between ions results from the electrostatic attraction of opposite charges.
A.how many moles of aspirin are in one tablet
0.325 g ( 1 mol / 180.2 g ) = 1.80 x 10^-3 mol
B. How many moles of oxygen are in one tablet of aspirin
1.80 x 10^-3 mol C9H8O4 ( 4 mol O / 1 mol <span>C9H8O4) = 7.21 x 10^-3 mol O
</span>
C. How many atoms of carbon are in one tablet of aspirin
1.80 x 10^-3 mol C9H8O4 ( 9 mol C / 1 mol C9H8O4 ) ( 6.022 x 10^23 atoms C / 1 mol C ) = 9.76 x 10^21 atoms C
D. How many grams of oxygen in one tablet of aspirin
7.21 x 10^-3 mol O ( 16 g / mol ) = 0.12 g O
They have used added new elements to the table .
<u>Explanation:</u>
As new elements are discovered chemists add them to the period table leading to the periodic table undergoing continuous modifications. When the first periodic table in the world was formed, very few elements were known to humankind. Earlier periodic tables thus contain lesser number of elements than the modern ones.
Mendeleev's periodic table contained 63 elements arranged in the increasing order of their atomic masses. Modern periodic tables have far more number then the older ones like that of Mendeleev's and the elements are arranged in the order of their atomic numbers.
