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3 years ago

Mg(OH)2 + 2 HBr à MgBr2 + 2 H2O

Chemistry

1 answer:

AnnyKZ [126]3 years ago

5 0

Explanation:

The balanced equation of the reaction is given as;

Mg(OH)2 (s) + 2 HBr (aq) → MgBr2 (aq) + 2 H2O (l)

1. How many grams of MgBr2 will be produced from 18.3 grams of HBr?

From the reaction;

2 mol of HBr produces 1 mol of MgBr2

Converting to masses using;

Mass = Number of moles * Molar mass

Molar mass of HBr = 80.91 g/mol

Molar mass of MgBr2 = 184.113 g/mol

This means;

(2 * 80.91 = 161.82g) of HBr produces (1 * 184.113 = 184.113g) MgBr2

18.3g would produce x

161.82 = 184.113

18.3 = x

x = (184.113 * 18.3 ) / 161.82 = 20.8 g

2. How many moles of H2O will be produced from 18.3 grams of HBr?

Converting the mass to mol;

Number of moles = Mass / Molar mass = 18.3 / 80.91 = 0.226 mol

From the reaction;

2 mol of HBr produces 2 mol of H2O

0.226 mol would produce x

2 =2

0.226 = x

x = 0.226 * 2 / 2 = 0.226 mol

3. How many grams of Mg(OH)2 are needed to completely react with 18.3 grams of HBr?

From the reaction;

2 mol of HBr reacts with 1 mol of Mg(OH)2

18.3g of HBr = 0.226 mol

2 = 1

0.226 = x

x = 0.226 * 1 /2

x = 0.113 mol

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Answer: 17 years

Explanation:

Expression for rate law for first order kinetics for radioactive substance is given by:

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where,

k = rate constant

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a = let initial amount of the reactant

a - x = amount left after decay process

a) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

$t_{\frac{1}{2}}=\frac{0.693}{k}$

$k=\frac{0.693}{82years}=8.4\times 10^{-3}years^{-1}$

b) for 8900 g of the mass of the sample to reach 7700 grams

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3 years ago

Calculate the molality of a solution containing 15.01 g of glycerol (c 3h 8o 3) in 42.3 g of ethanol (c 2h 5oh).

kkurt [141]

The molality of the glycerol solution is 3.854mol/kg

The number of moles of solute present in a solution equal to 1 kg or 1000 g of solvent is referred to as its molality.

Given:

Mass, m1 of glycerol = 15.01g

Mass, m2 of ethanol = 42.3g

Molar mass, mm1 of glycerol = 92.095g/mol

Molar mass, mm2 of ethanol = 46.069g/mol

To find:

Molality, m = ?

Formula:

Molality, m = moles of solute / kg of solvent

Calculations:

No. of moles of glycerol = 15.01 x (1/92.095)

n = 0.163 mols

Molality, m = 0.163 / 0.0423g

Molality, m = 3.854mol/kg

Result:

3.854mol/kg is the molality of the glycerol solution.

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A solution of saturated pbi2 is found to contain 2.7 ✕ 10−3 m iodide ion. calculate the ksp of pbi2

BigorU [14]

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