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3 years ago

A 44.0 ml volume of 0.25 m hbr is titrated with 0.50 m koh. calculate the ph after addition of 22.0 ml of koh at 25 ∘c.

1 answer:

4 0

The reaction between KOH and HBr is as follows ;
KOH + HBr ---> H₂O + KBr
Stoichiometry of base to acid is 1:1 molar ratio
Both are strong acid and strong base therefore complete ionization takes place
The number of KOH moles added - 0.50 M / 1000 mL/L x 22 mL = 0.011 mol
the number of HBr moles - 0.25 M /1000 mL/L x 44 mL = 0.011 mol
the number of H⁺ ions and OH⁻ ions are equal therefore the whole amount of acid has been completely neutralised by base.
No remaining acid nor base, therefore solution is neutral.
pH = 7
thats the pH value for a neutral solution

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Answer:

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2 years ago

The complete combustion of a sample of propane produced 2.641 grams of carbon dioxide and 1.442 grams of water as the only produ

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A general equation for a combustion reaction would be expressed as follows:

CxHy + (x+y/2)O2 = xCO2 + y/2H2O

Propane would obviously would only have carbon and hydrogen in its structure. Assuming a complete combustion, all of the carbon atoms would go to carbon dioxide and all of the hydrogen atoms to water. To determine the empirical, we determine the number of carbon and hydrogen atoms present.

moles C = 2.461 g CO2 ( 1 mol / 44.01 g ) ( 1 mol C / 1 mol CO2 ) = 0.06 mol C

moles H = 1.442 g H2O ( 1 mol / 18.02 g ) ( 2 mol H / 1 mol H ) = 0.16 mol H

Then, we divide the smallest amount to the each mole of the atoms. We do as follows:

C = 0.06 / 0.06 = 1
H = 0.16 / 0.06 = 2.67

Then we multiply a number in order to obtain a whole number ratio between the atoms.

1 CH2.67
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8 0

2 years ago

Identify the products in the equation below (the “I” is Iodine—to differentiate capital “I” from lowercase “l”)

Inessa [10]

Answer : The products are Silver sulfide, $(Ag_2S)$ and Sodium iodide, $(NaI)$ .

Explanation :

The given balanced chemical reaction is,

$2AgI+Na_2S\rightarrow Ag_2S+2NaI$

From the given balanced reaction, we conclude that the 2 moles of silver iodide react with the 1 mole of sodium sulfide to give product as 1 mole of silver sulfide and 2 moles of sodium iodide.

In a chemical reaction, reactants are represent on the left side of the right-arrow and products are represent on the right side of the right-arrow.

Therefore, in a chemical reaction the products are Silver sulfide and Sodium iodide.

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3 years ago

7. A square chunk of plastic has a length of 5 cm, width of 5 cm and height of 5 cm. It has a mass of 200 g. What is its density

BaLLatris [955]

Answer:

$d=1.6\ g/cm^3$

Explanation:

Given that,

The dimension of a square chunk of plastic is 5 cm × 5 cm × 5 cm

Mass, m = 200 g

We need to find its density

Density = mass/volume

It will form a cube. It volume = side³

So,

$d=\dfrac{200\ g}{5^3\ cm^3}\\\\d=1.6\ g/cm^3$

Hence density is $1.6\ g/cm^3$

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3 years ago

A compound in a copper ore has the following percentage composition by mass:

AveGali [126]

1) since we are given percentages, we can assume we have 100 grams of the molecule.

55.6 % Cu ----> 55.6 grams Cu
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2) convert each gram to moles using the molar masses given

$55.6 g Cu \frac{1 mol}{63.5 g} = 0.876 mol Cu$
$16.4 g Fe \frac{1 mol}{56.0 g} = 0.293 mol Fe$
$28.0 gS \frac{1 mol}{32.0} = 0.875 mol S$

3) we divide the smallest value of moles (0.293) to each one.

Cu --> 0.876 / 0.293= 3
Fe---> 0.293 / 0.293= 1
S-----> 0.875 / 0.293= 3

4) let's write the empirical formula

Cu₃FeS₃

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2 years ago