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3 years ago

Why do we need to standardize EDTA in determination of water hardness?

1 answer:

3 0

Standardized means that a specific amount EDTA is added to a specific volume of distilled water. Water hardness is determined by the the amount of a standard EDTA solution to change the color of the water from red to blue. For example if one added the correct amount of EDTA to twice the volume of distilled water the solution would be weak. Titration of the hard water would give a erroneous high result.

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Crude oil is a mixture of many liquids. The crude oil enters the bottom of a tall column, where the mixture is heated. The subst

Yanka [14]

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3 years ago

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How many grams of lead(II) sulfate (303 g/mol) are needed to react with sodium chromate (162 g/mol) in order to produce 0.162 kg

Afina-wow [57]

Answer : The mass of $PbSO_4$ needed are, 1.515 grams.

Explanation :

First we have to calculate the mole of $PbCrO_4$ .

$\text{Moles of }PbCrO_4=\frac{\text{Mass of }PbCrO_4}{\text{Molar mass of }PbCrO_4}=\frac{0.162g}{323g/mole}=0.005mole$

Now we have to calculate the moles of $PbSO_4$ .

The balanced chemical reaction will be,

$PbSO_4+Na_2CrO_4\rightarrow PbCrO_4+Na_2SO_4[tex]From the balanced chemical reaction, we conclude thatAs, 1 mole of [tex]PbCrO_4$ produced from 1 mole of $PbSO_4$

So, 0.005 mole of $PbCrO_4$ produced from 0.005 mole of $PbSO_4$

Now we have to calculate the mass of $PbSO_4$

$\text{Mass of }PbSO_4=\text{Moles of }PbSO_4\times \text{Molar mass of }PbSO_4$

$\text{Mass of }PbSO_4=0.005mole\times 303g/mole=1.515g$

Therefore, the mass of $PbSO_4$ needed are, 1.515 grams.

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2 years ago

a square boat made from iron has overall dimensions of 2.00 cm x 11.0 cm x 11.0 cm. it has a mass of 213 g. water has a density

Stolb23 [73]

Density of boat = $\frac{MASS}{VOLUME}$

= $\frac{213 g}{(2 cm * 11 cm * 11cm)}$

= 0.88 g / cm³

Since the density of water is greater than the density of the boat ( 1 > 0.88) then that means, the boat will NOT sink.

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3 years ago

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A lake in rural maine drops in ph from 7 to 5 as a result of acid rain falling into it. how has the h+ ion concentration change

Jlenok [28]

The H+ concentration in the lake has increased as a result of the acid rain.
The original pH of the lake was 7, which mean the water is neutral, but due to the acid rain, it drops to 5. This means, that the water has become acidic and how have more hydrogen ion. The H+ concentration in the lake has 100 times compares with its original pH.

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3 years ago

How does a higher heat capacity affect the amount of time it takes for an object’s temperature to change?

marshall27 [118]

<span> An object with a high specific heat would change temperature more slowly than one with low specific heat. Water, for example has a very high specific heat so it requires a lot of energy to heat it up. It also takes a while for water to cool down because it holds that heat for a long time. <3</span>

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3 years ago

Why do we need to standardize EDTA in determination of water hardness?​

Why do we need to standardize EDTA in determination of water hardness?