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Tasya [4]
3 years ago
14

Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of wate

r molecules are included in the solid structure. Its formula can be written as Na₂CO₃⋅xH₂O, where x is the number of moles of H₂O per mole of Na₂CO₃. When a 3.837 −g sample of washing soda is heated at 25 ∘C, all the water of hydration is lost, leaving 1.42 g of Na₂CO₃.
What is the value of x?
Chemistry
1 answer:
nadya68 [22]3 years ago
4 0

Answer:

moles H₂O = 10

Explanation:

The mass of Na₂CO₃⋅xH₂O is 3.837 g and the mass of Na₂CO₃ is 1.42g

Therefore the mass of xH₂O is 3.837 - 1.42 = 2.417 g

The molar mass of Na₂CO₃ is 106 g/mol and for H₂O is 18 g/mol

The moles of Na₂CO₃ and H₂O in the sample are:

Na₂CO₃ = 1.42 / 106 = 0.01340 moles

H₂O = 2.417 / 18 = 0.1343

Now using rule of three :

1 mole of Na₂CO₃ has x moles of H₂O

0.01340 moles of Na₂CO₃ has 0.1343 moles of H₂O

x = 1 * 0.1343 / 0.01340 = 10

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Irina18 [472]

Any substance changes to another substance that means the change of the physical property. Like water () has different state which changes as the temperature changes. It remain as liquid in the room temperature, in solid form at or below 0°C and vapor phase on or above 100°C. But in all the stage or phase of the substance the composition of the water i.e.  remains. Thus the chemical property remains fixed when a substance change to other substance.  

3 0
3 years ago
Calculate the pH of a 2.3 10-3M[OH'] solution.
disa [49]

Answer:

11.33

Explanation:

-log(2.3x10^-3) = 2.67

14-2.67

- Hope this helped! Let me know if you need a further explanation.

5 0
3 years ago
A solid substance that has a naturally geometric shape with symmetrically arranged plane faces
Arisa [49]
It is a Crystalline
3 0
2 years ago
Read 2 more answers
When 70.4 g of benzamide (C7H7NO) are dissolved in 850. g of a certain mystery liquid X, the freezing point of the solution is 2
Arlecino [84]

Answer:

1.62

Explanation:

From the given information:

number of moles of benzamide  =\dfrac{70.4 \ g}{121.14 \ g/mol}

= 0.58 mole

The molality = \dfrac{mass \ of \ solute (i.e. \ benzamide )}{mass \ of \ solvent  }

= \dfrac{0.58 }{0.85 }

= 0.6837

Using the formula:

\mathbf {dT  = l   \times  k_f  \times m}

where;

dT = freezing point = 27

l = Van't Hoff factor = 1

kf = freezing constant of the solvent

∴

2.7 °C = 1 × kf ×  0.6837 m

kf = 2.7 °C/ 0.6837m

kf = 3.949 °C/m

number of moles of NH4Cl = \dfrac{70.4 \ g}{53.491 \  g /mol}

= 1.316 mol

The molality = \dfrac{1.316 \ mol}{0.85 \ kg}

= 1.5484

Thus;

the above kf value is used in determining the  Van't Hoff factor for  NH4Cl

i.e.

9.9 = l × 3.949 × 1.5484 m

l = \dfrac{9.9}{3.949 \times 1.5484 \ m}

l = 1.62

5 0
2 years ago
What is the mass of 8.0 x 10^26 UF6 molecules?
gulaghasi [49]
First, find the number of moles of UF6
Avagadro's number = 6.023 x 10^23

Number of moles = 8.0 x 10^26 / Avagadro's number = 8.0 x 10^26 / 6.023 x 10^23 = 1.328 x 10³ moles

Molecular weight of UF6 = Molecular weight of U (238.02891) + Molecular weight of F6 (6 x 18.9984032) = 238.02891 + 113.9904192 = 352.0193292 g/mol

Therefore mass of 8.0 x 10^26 UF6 molecules = 352.0193292 g/mol x 1.328 x 10³ moles = 467.481669 x 10³ grams




3 0
2 years ago
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