Advertisements
Advertisements
Question
The percentage composition of sodium phosphate, as determined by analysis is : 42.1% Na, 18.9% P, 39% of O. Find the empirical formula of the compound.
[H =1, N =14, Na = 23, P = 31, Cl = 35.5, Pt = 195]
Advertisements
Solution
| Element | Atomic mass | Percentage | Relative ratio of moles | Simplest mole ratio | Whole number ratio |
| Na | 23 | 42.1 | 42.1/23 = 1.8 | 1.8/0.6 =3 | 3 |
| P | 31 | 18.9 | 18.9/31 = 0.6 | 0.6/0.6 = 1 |
1 |
| O | 16 | 39 |
39/16 |
2.4/0.6 = 4 | 4 |
Empirical formula = Na3PO4.
APPEARS IN
RELATED QUESTIONS
Consider the following reaction and based on the reaction answer the questions that follow:
Calculate:
1) the quantity in moles of (NH4)2Cr2O7 if 63gm of(NH4)2Cr2O7 is heated.
2) the quantity in moles of nitrogen formed.
3) the volume in liters or dm3 of N2 evolved at S.T.P.
4) the mass in grams of Cr2O3 formed at the same time
(Atomic masses: H=1, Cr= 52, N=14]
A compound made up of two elements X and Y has an empirical formula X2Y. If the atomic weight of X is 10 and that of Y is 5 and the compound ha a vapor density 25, find its molecular formula.
The compound A has the following percentage composition by mass: C =26.7%, O = 71.1%, H = 2.2%.
Determine the empirical formula of A.(Answer to one decimal place) (H=1,C=12,O=16)
Determine the empirical formula of the compound whose composition by mass is 42% nitrogen, 48% oxygen and 9% hydrogen.[N=14,O=16,H=1]
A compound 'X' consists of 4.8% of C and 95.2% of Br by mass.
Determine the empirical formula of this compound.
[C = 12, Br = 80]
Calculate the percentage of water of crystallization in CuSO4. 5H2O
(H = 1, O = 16, S = 32, Cu = 64)
Find the percentage of mass water in Epsom salt MgSO4.7H2O.
Explain the term empirical formula.
In a compound of magnesium (Mg = 24) and nitrogen (N = 14), 18 g of magnesium combines with 7g of nitrogen.
Deduce the simplest formula by answering the following questions:
- How many gram-atoms of magnesium are equal to 18g?
- How many gram-atoms of nitrogen are equal to 7g of nitrogen?
- Calculate the simple ratio of gram-atoms of magnesium to gram-atoms of nitrogen and hence the simplest formula of the compound formed.
A compound has the following percentage composition by mass: carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. By what type of reaction could this compound be obtained from ethylene?
