A stock solution of ammonia in water is 28 wt% NH3. The Formal Weight (FW) of NH3 is 17.03 g/mol). The solution density at room temperature is 0.90 g/mL. What is the molarity of the solution in units of mol/L

[NH₃] = 14.7 mol/L

Explanation:

28 wt% is a type of concentration that indicates that 28 g of ammonia is contained in 100 g of solution.

Let's determine the amount of ammonia:

28 g . 1 mol / 17.03g = 1.64 moles of NH₃

You need to consider that, when you have density's data it is always referred to solution:

Mass of solution is 100 g, let's find out the volume

0.90 g/mL = 100 g /V

V = 100 g / 0.90mL/g → 111.1 mL

We convert the volume to L → 111.1 mL . 1 L/1000mL = 0.1111 L

mol/L = 1.64 mol/0.1111L → 14.7 M

mol/L = M → molarity a sort of concentration that indicates the moles of solute in 1L of solution

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.