Answer:
Explanation:
A property closely related to an atom's mass number is its atomic mass. The atomic mass of a single atom is simply its total mass and is typically expressed in atomic mass units or amu.
Reaction of Elemental Calcium with Water is as follow,
Ca + 2 H₂O → Ca(OH)₂ + H₂↑
When Sodium Metal is reacted with Water it produces NaOH and eliminates Hydrogen gas as shown in following equation,
2 Na + 2 H₂O → 2 NaOH + H₂↑
In both cases corresponding Hydroxides along with Hydrogen gas is produced.
Answer:
C. H2O is the base and H3O+ is the conjugate acid
Explanation:
According to Bronsted-Lowry acid-base theory, an acid is a substance that loses an hydrogen ion or proton (H+) while a base is a substance that gains an hydrogen ion (H+) or proton. Furthermore, this theory states that, the molecule formed when an acid donates its proton is called the CONJUGATE BASE, while the molecule formed when the base accepts proton is called CONJUGATE ACID.
In this question, the following equation is given:
NH4+(aq) + H2O(aq) ⇌NH3(aq) + H3O+ (aq)
Water (H2O) is the base in this equation because according to Bronsted-Lowry acid-base theory, it accepts an hydrogen ion (H+) while hydroxonium ion (H3O+) is the conjugate acid.
Answer:
Approximately 75%.
Explanation:
Look up the relative atomic mass of Ca on a modern periodic table:
There are one mole of Ca atoms in each mole of CaCO₃ formula unit.
- The mass of one mole of CaCO₃ is the same as the molar mass of this compound:
. - The mass of one mole of Ca atoms is (numerically) the same as the relative atomic mass of this element:
.
Calculate the mass ratio of Ca in a pure sample of CaCO₃:
.
Let the mass of the sample be 100 g. This sample of CaCO₃ contains 30% Ca by mass. In that 100 grams of this sample, there would be
of Ca atoms. Assuming that the impurity does not contain any Ca. In other words, all these Ca atoms belong to CaCO₃. Apply the ratio
:
.
In other words, by these assumptions, 100 grams of this sample would contain 75 grams of CaCO₃. The percentage mass of CaCO₃ in this sample would thus be equal to:
.