The required mass of calcium bromide is 35.98 grams.
<h3>What is molarity?</h3>
Molarity is any solution is define as the number of moles of solute present in per liter of solution as;
M = n/V, where
- M = molarity = 4M
- V = volume = 45mL = 0.045L
Moles will be calculated by using the above equation as:
n = (4)(0.045) = 0.18 mole
Relation between the mass and moles of any substance will be represented as:
n = W/M, where
- W = given mass
- M = molar mass
Mass of CaBr₂ = (0.18mol)(199.89g/mol) = 35.98g
Hence required mass of CaBr₂ is 35.98 grams.
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Answer:
- <em>Hydration number:</em> 4
Explanation:
<u>1) Mass of water in the hydrated compound</u>
Mass of water = Mass of the hydrated sample - mass of the dehydrated compound
Mass of water = 30.7 g - 22.9 g = 7.8 g
<u>2) Number of moles of water</u>
- Number of moles = mass in grams / molar mass
- molar mass of H₂O = 2×1.008 g/mol + 15.999 g*mol = 18.015 g/mol
- Number of moles of H₂O = 7.9 g / 18.015 g/mol = 0.439 mol
<u>3) Number of moles of Strontium nitrate dehydrated, Sr (NO₃)₂</u>
- The mass of strontium nitrate dehydrated is the constant mass obtained after heating = 22.9 g
- Molar mass of Sr (NO₃)₂ : 211.63 g/mol (you can obtain it from a internet or calculate using the atomic masses of each element from a periodic table).
- Number of moles of Sr (NO₃)₂ = 22.9 g / 211.63 g/mol = 0.108 mol
<u>4) Ratio</u>
- 0.439 mol H₂O / 0.108 mol Sr(NO₃)₂ ≈ 4 mol H₂O : 1 mol Sr (NO₃)₂
Which means that the hydration number is 4.
Answer:
[Cr(NH3)6.]C13
Explanation:
Alfred Werner's coordination theory (1893) recognized two kinds of valency;
Primary valency which are nondirectional and secondary valency which are directional.
Hence, the number of counter ions precipitated from a complex depends on the primary valency of the central metal ion in the complex.
We must note that it is only these counter ions that occur outside the coordination sphere that can be precipitated by AgNO3.
If we consider the options carefully, only [Cr(NH3)6.]C13 possess counter ions outside the coordination sphere which can be precipitated when treated with aqueous AgNO3.
