The difference of molarity and molality is in the units:
Molarity is expressed in mol solute / L solution;
<span> while Molality is
expressed in mol solute / kg solvent</span>
Since no other data is given, let us assume that the
contribution of methanol on the total volume is negligible. So that,
Molality = (20.3 mol / L) (1 L / 0.858 kg)
Molality = 23.66 m
<span>The closest answer is letter C. 23.7 m</span>
Answer:
The correct option is the second option
Explanation:
Generally, the aim of science is to understand a particular concept in the best and the most correct way possible; hence experiments are done and repeated to ensure an explanation is actually true about a concept or need modification.
The atomic models have also been a "beneficiary" of this process. The different atomic models are usually been improved upon as scientists leaned more. For example, the Dalton's atomic theory has been modified to a more correct atomic description; some of which are shown below
(1) Dalton's theory suggested that an atom is the smallest unit of a molecule. We know now from different experiments (by J. J Thompson and Rutherford) that atoms are not the smallest molecules and are made up of smaller particles known as protons, neutrons and electrons.
(2) Dalton's theory suggested that atoms of the same elements are alike in all aspects. The knowledge of isotopy shows this is not always the case. As atoms of the same elements (isotopes) have the same atomic number but different mass number; hence cannot be said to be the same in all aspects.
(3) Dalton's theory also suggested that when atoms react, they do so in fixed, simple whole number ratio. The knowledge of organic chemistry shows atoms do not always react in simple whole number ratios
There are several modifications to different postulations by scientists that have also occurred aside from this, hence the most correct answer is that "As scientists learned more, they modified the atomic model"
Answer:
The steps are explained below, the essential step is to find mass here, 120 g of NaOH.
Explanation:
In order to answer this question, we need to define molarity conceptually firstly to see what variables we need. According to the formula, molarity is equal to the ratio between moles and volume, while moles itself is a ratio between mass and molar mass. This means we have a formula for molarity involving mass, molar mass and volume:
In order to prepare a 500.0 mL of stock solution of 6.0 M of NaOH, we then need to find the mass of NaOH dissolved in this solution using the equation above:
Now, since we have the mass of NaOH, we can describe the steps needed to prepare this solution:
- measure 120 grams of solid NaOH;
- add this mass of NaOH into a 500.0-mL Erlenmeyer flask;
- fill approximately half of the flask with distilled water and stir gently to make sure that NaOH dissolves, if it doesn't, add more water and repeat the process;
- when NaOH fully dissolves, fill the flask to the mark.
Our solution is prepared.
