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sveta
14 days ago
8

A careless laboratory technician wants to prepare 200.0 mL of a 0.025 m HCl(aq) solution but uses a volumetric flask of vol- ume

250.0 mL by mistake. (a) What would the pH of the desired solution have been? (b) What will be the actual pH of the solution as prepared?
Chemistry
1 answer:
KiRa [2.8K]14 days ago
4 0

Answer:

a) 0.9030 b) 1

Explanation:

The pH is determined by calculating the negative logarithm of the hydrogen ion concentration of a solution. When HCl dissociates in water, it produces 1 mole of hydrogen ion concentration; similarly, if 0.025 m of HCl dissociates in water, it yields 0.025 moles of hydrogen ions.

For HCl's molarity in a 200 mL solution = moles / volume in liters = 0.025 / ( 200/1000) = 0.125 M

pH = log base 10 ( 0.125^ -1) = 0.903

Calculating the molarity of HCl in 250 mL = 0.025 / (250/1000) = 0.1 M

pH = log base 10 ( 0.1^-1) = 1

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A student is given a sample of a blue copper sulfate hydrate. He weighs the sample in a dry covered porcelain crucible and got a
KiRa [2853]

Answer:

There are 5.5668 moles of water for every mole of CuSO₄.

Explanation:

The mass of anhydrous CuSO₄ is:

23.403g - 22.652g = 0.751g.

mass of crucible + lid + CuSO₄ - mass of crucible + lid

Given that the molar mass of CuSO₄ is 159.609g/mol, we calculate the moles:

0.751g ×\frac{1mol}{159,609g} = 4.7052x10⁻³ moles CuSO₄

The mass of water in the initial sample is:

23.875g - 0.751g - 22.652g = 0.472g.

mass of crucible + lid + CuSO₄ hydrate - CuSO₄ - mass of crucible + lid

As the molar mass of H₂O is 18.02g/mol, we find the moles:

0.472g ×\frac{1mol}{18,02g} = 2.6193x10⁻² moles H₂O

The mole ratio of H₂O to CuSO₄ is:

2.6193x10⁻² moles H₂O / 4.7052x10⁻³ moles CuSO₄ = 5.5668

This indicates there are 5.5668 moles of water per mole of CuSO₄.

I hope this is helpful!

5 0
1 month ago
What is the density (in g/L) of a gas with a molar mass of 16.01 g/mol at 1.75 ATM and 337 K?
Anarel [2728]
To solve for density, you can use the formula--> Density= PM/ RT, where P stands for pressure, M for molar mass, R represents the gas constant, and T is temperature. 

P= 1.75 atm
M= 16.01 g/ mol
R= 0.0821 atm·L/ mol·K
T=337 k

Thus, the density calculation becomes: density= (1.75 x 16.01)/ (0.0821 x 337)= 1.01 g/L
8 0
12 days ago
Read 2 more answers
The following five beakers, each containing a solution of sodium chloride (NaCl, also known as table salt), were found on a lab
Anarel [2728]

Answer:

Please review the following responses

Explanation:

1) A solution of 100. mL contains 19.5 g of NaCl  (3.3M)

2) 100. mL of NaCl solution at 3.00 M (3 M)

3) A solution of 150. mL holds 19.5 g of NaCl  (2.2 M)

4) The concentrations of beakers 1 and 5 are identical (1.5M)

Molar mass of NaCl = 23 + 36 = 59 g

For beaker number 3:

          59 g -------------- 1 mol

           19.5 g -------------   x

  x = 19.5 x 1/59 = 0.33 mol

Molarity (M) = 0.33 mol/0.150 l = 2.2 M

For beaker number 4:

Molarity (M) = 0.33mol/0.10 l = 3.3 M

For beaker number 5:

Molarity (M) = 0.450/0.3 = 1.5 M

4 0
1 month ago
Read 2 more answers
Assume the weight of an average adult is 70. kg, and that 420. kJ of heat are evolved per mole of oxygen consumed as a result of
castortr0y [2906]
The temperature difference after 3 hours is 5.16 K. Given that the moles of O₂ inhaled rate at 0.02 mole/min, which converts to 1.2 mole/hour, we know the average heat released during metabolism is 7.2 kJ/h·kg. Therefore, the amount of heat generated within 3 hours will be 7.2 kJ/h·kg multiplied by 3 hours, giving a result of 21.6 kJ/kg, or 21.6 x 10³ J/kg. Applying the formula Qp = Cp x ΔT, and taking the body's heat capacity to be 4.18 J/g·K, we find ΔT = 5.16 K.
6 0
13 days ago
If the chemical reaction AB + CD ⟶ AD + BC releases heat, what is true of the stored bond energy of the reactants and products?
lorasvet [2668]
The accurate choice is the final one.
3 0
22 days ago
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