Chemistry, 31.01.2020 06:54 kang39

Arock sample weighing 5.88 x 10-4 g is known to contain calcium, phosphorus, and oxygen. the amount of the first two elements in this rock is found to be 2.28 x 10-4 g and 1.18 x 10-4 g respectively. what is the empirical formula for the compound in this rock sample?

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Answer from: medlinalex

Ca₃P₂O₈.

Explanation:

Firstly, we can determine the mass of oxygen:

The mass of oxygen in the rock = the mass of the rock - (the mass of Ca + the mass of P) = (5.88 x 10⁻⁴ g) - (2.28 x 10⁻⁴ g + 1.18 x 10⁻⁴ g) = 2.42 x 10⁻⁴ g.

We need to determine the no. of moles of each element in the rock:

no. of moles = mass/atomic mass.

no. of moles of Ca = (2.28 x 10⁻⁴ g)/(40.078 g/mol) = 5.689 x 10⁻⁶ mol.

no. of moles of P = (1.18 x 10⁻⁴ g)/(30.97 g/mol) = 3.81 x 10⁻⁶ mol.

no. of moles of O = (2.42 x 10⁻⁴ g)/(16.0 g/mol) = 1.51 x 10⁻⁵ mol.

To find the mole ratio of (Ca: P: O), we divide by the lowest no. of moles that of P (3.81 x 10⁻⁶ mol).

The mole ratio of (Ca: P: O) will be ((5.689 x 10⁻⁶ mol)/(3.81 x 10⁻⁶ mol): (3.81 x 10⁻⁶ mol)/(3.81 x 10⁻⁶ mol): (1.51 x 10⁻⁵ mol)/(3.81 x 10⁻⁶ mol)).

∴ The mole ratio of (Ca: P: O) will be (1.5: 1.0: 4.0).

Multiplying by 2.0 to get the empirical formula of the rock:

The empirical formula of the rock is Ca₃P₂O₈.

Answer from: Quest

what is the general relationship between a galaxy's distance from earth and its speed?

the answer is:

the farther away a galaxy is from us, the faster it is moving away from us.

Answer from: Quest

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is $1s^{2}2s^{2}2p^{6}3s^{1}$ and electronic configuration of phosphorous is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$ .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

$3na + p \rightarrow na_{3}p$

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.