Answer:
3.0x10¹⁹ atoms
Explanation:
First we <u>convert 10 mg of mercury into grams</u>:
Then we <u>convert 0.01 g of mercury into moles</u>, using its <em>molar mass</em>:
- 0.01 g ÷ 200.59 g/mol = 4.99x10⁻⁵ mol
Then we <u>convert moles into number of atoms</u>, using <em>Avogadro's number</em>:
- 4.99x10⁻⁵ mol * 6.023x10²³ atoms/mol = 3.0x10¹⁹ atoms
Answer:
Explanation:
1.Calculate the freezing point depression
ΔTf = 0.00 °C - (-4.75 °C) = = 0.00 °C + 4.75 °C = 4.75 °C
2. Calculate the molal concentration
The formula for the freezing point depression by a nonelectrolyte is
Answer:
The percent by mass of water in this crystal is:
Explanation:
This exercise can be easily solved using a simple rule of three where the initial weight of the hydrated crystal (6,235 g) is taken into account as 100% of the mass, and the percentage to which the mass of 4.90 g corresponds (after getting warm). First, the values and unknown variable are established:
- 6,235 g = 100%
- 4.90 g = X
And the value of the variable X is found:
- X = (4.90 g * 100%) / 6,235 g
- X = approximately 78.6%.
The calculated value is not yet the percentage of the water, since the water after heating the glass has evaporated, therefore, the remaining percentage must be taken, which can be calculated by subtraction:
- Water percentage = Total percentage - Percentage after heating.
- <u>Water percentage = 100% - 78.6% = 21.4%</u>
Answer:
1- Dropping a sliced orange into a vat of Sodium Dydroxide
Explanation:
The other answers (2-4) are only physical changes that don't change any chemical compositions.
