Glauber's salt consists of crystals of hydrated sodium sulfate, $$$\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot \times \mathrm{H}_{2} \mathrm{O}$$$, which can be used for the manufacture of detergents. When a sample of Glauber's salt was heated, 1.91 g of water was removed leaving 1.51 g of anhydrous $$$\mathrm{Na}_{2} \mathrm{SO}_{4}$$$. What is the value of $$$x$$$ in $$$\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot \mathrm{xH}_{2} \mathrm{O}$$$ ?

8.85

11.25

Chemistry

IGCSE&ALevel

CAIE

Exam No：9701_w24_qp_11 Year：2024 Question No：3

Answer:

Knowledge points:

2.1.1 define the unified atomic mass unit as one twelfth of the mass of a carbon-12 atom

2.1.2 define relative atomic mass, Ar, relative isotopic mass, relative molecular mass, Mr, and relative formula mass in terms of the unified atomic mass unit

2.3.1.1 the prediction of ionic charge from the position of an element in the Periodic Table

2.3.1.2 recall of the names and formulae for the following ions:

2.3.2 write and construct equations (which should be balanced), including ionic equations (which should not include spectator ions)

2.3.3 use appropriate state symbols in equations

2.3.4 define and use the terms empirical and molecular formula

2.3.5 understand and use the terms anhydrous, hydrated and water of crystallisation calculate empirical and molecular formulae, using given data

Answer:

Knowledge points:

Solution:

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