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3 years ago

What mass of water must be added to 5g of nacl to make 5% mass persentage of the solution?

Chemistry

1 answer:

Vitek1552 [10]3 years ago

8 0

Answer:-

95 grams

Explanation:-

Let the mass of water to be added be M

So total mass = 5 + M

So 5% of this solution has 5g of NaCl by mass.

∴ (M+5) x (5/100) = 5

M+5 = 5 x 100/5

M+5=100

M= 100-5

So amount of water to be added is 95 gram

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dsp73

Answer:

True

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3 years ago

If a sample of gas is located 10.2 cm from the injection point and the chart speed is 0.5 cm/min, what is the retention time?

Archy [21]

Answer : The retention time is, 20 min

Explanation :

Retention time : It is defined as the amount of time a compound spends on the column after it has been injected.

Formula of retention time is:

$\text{Retention time}=\frac{\text{Distance from injection point to center of peaks}}{\text{Chart recorded speed}}$

Given:

Distance from injection point to center of peaks = 10 cm

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Now put all the given values in the above formula, we get:

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Thus, the retention time is, 20 min

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3 years ago

The standard enthalpy change for the following reaction is 873 kJ at 298 K.

Flura [38]

Answer: - 436.5 kJ.

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation.

The given chemical reaction is,

$2KCl(s)\rightarrow 2K(s)+Cl_2(g)$ $\Delta H_1=873kJ$

Now we have to determine the value of $\Delta H$ for the following reaction i.e,

$K(s)+\frac{1}{2}Cl_2(g)\rightarrow KCl(s)$ $\Delta H_2=?$

According to the Hess’s law, if we divide the reaction by half then the $\Delta H$ will also get halved and on reversing the reaction , the sign of enthlapy changes.

So, the value $\Delta H_2$ for the reaction will be: