Question

Яку масу води і солі потрібно взяти,щоб виготовити 40 г розчину з масовою часткою солі 2,5%?

Answer 1

M(cолі) = 40 г*0,025 = 1 г
m(H2O) = 40 г - 1 г = 39 г
Відповідь: 1 г солі та 39 г води

Answer 2

I can chat with you in Ukrainian. You asked me to answer in detail. How much water and salt do you need to take to make 40 g of solution with a mass fraction of salt 2.5%?

To make a solution with a mass fraction of salt 2.5%, you need to use the following formula:

$$w/v = (m_s \div V_s) \times 100$$

where $w/v$ is the mass fraction of salt in percentage, $m_s$ is the mass of salt in grams, and $V_s$ is the volume of solution in milliliters.

To find the mass of salt, you need to rearrange the formula as follows:

$$m_s = (w/v \times V_s) \div 100$$

To find the volume of solution, you need to use the density of the solution, which depends on the concentration of salt. According to [this table](https://www.physiologyweb.com/calculators/percent_solutions_calculator.html), the density of a 2.5% salt solution is 1.012 g/mL. Therefore, the volume of solution is equal to the mass of solution divided by the density of solution:

$$V_s = m_s \div d_s$$

where $d_s$ is the density of solution in g/mL.

Substituting the values given in the question, we get:

$$V_s = 40 \div 1.012 \approx 39.53 \text{ mL}$$

$$m_s = (2.5 \times 39.53) \div 100 \approx 0.99 \text{ g}$$

Therefore, to make 40 g of solution with a mass fraction of salt 2.5%, you need to take about 0.99 g of salt and 39.53 mL of water.

To prepare the solution, you can follow these steps:

- Place the salt in a 100-mL volumetric flask. - Add a small volume of distilled, deionized water to dissolve the salt. - Fill the flask to the 100 mL line with more water. - Cap the flask and shake well to mix the solution.

I hope this helps you. If you have any other questions, feel free to ask me.