Chem Stoichiometry, questions in Pic<br><br> Thanks )

Which element would most likely have a positive electron affinity

STatiana [176]

Answer : Electron affinity (Eea) of an atom or molecule can be defined as the amount of energy released or spent when an electron is being added to a neutral atom or molecule in the gaseous state to form a negative ion.

Chlorine is considered to be the element which has highest electron affinity in the modern periodic table.

The general formula is X + $e^{-}$ ----> $X^{-}$ + energy

It is found that nonmetals have more positive Eea than metals.

Electron affinity increases across the group from left to right in the modern periodic table. Elements with small nucleus have high electron affinity.

7 0

2 years ago

Suppose you have just added 200.0 ml of a solution containing 0.5000 moles of acetic acid per liter to 100.0 ml of 0.5000 M NaOH

uranmaximum [27]

Answer:

The final pH is 3.80

Explanation:

Step 1: Data given

Volume of acetic acid = 200.0 mL = 0.200 L

Number of moles acetic acid = 0.5000 moles

Volume of NaOH = 100.0 mL = 0.100 L

Molarity of NaOH = 0.500 M

Ka of acetic acid = 1.770 * 10^-5

Step 2: The balanced equation

CH3COOH + NaOH → CH3COONa + H2O

Step 3: Calculate moles

moles = molarity * volume

Moles NaOH = 0.500 M * 0.100 L

Moles NaOH = 0.0500 moles

Step 4: Calculate the limiting reactant

For 1 mol CH3COOH we need 1 mol NaOH to produce 1 mol CH3COONa and 2 moles H2O

NaOH is the limiting reactant. It will completely be consumed (0.0500 moles). CH3COOH is in excess. There will react 0.0500 moles . There will remain 0.500 - 0.0500 = 0.450 moles

There will be produced 0.0500 moles CH3COONa

Step 5: Calculate the total volume

Total volume = 200.0 mL + 100.0 mL = 300.0 mL

Total volume = 0.300 L

Step 6: Calculate molarity

Molarity = moles / volume

[CH3COOH] = 0.450 moles / 0.300 L

[CH3COOH] = 1.5 M

[CH3COONa] = 0.0500 moles / 0.300 L

[CH3COONa]= 0.167 M

Step 7: Calculate pH

pH = pKa + log[A-]/ [HA]

pH = -log(1.77*10^-5) + log (0.167/ 1.5)

pH = 4.75 + log (0.167/1.5)

pH = 3.80

The final pH is 3.80

7 0

3 years ago

Which of these solutes raises the boiling point of water the most?

sergey [27]

Answer:

D. ionic sodium phosphate (Na3PO4)

Explanation:

Molecule for molecule, the solute that raises the boiling point of water the most is the one that makes the most particles in the solution. Lithium chloride breaks up into two ions (Li+ and Cl-). So does sodium chloride (Na+ and Cl-). Molecular molecules don't break up at all, so sucrose has only 1 particle per molecule. Sodium phosphate makes 4 total particles (3 Na+ ions and 1 PO4^3-). And magnesium bromide would make 3 particles (1 Mg2+ and 2 Br-). So the most is 4.

6 0

3 years ago

why did mendeleev leave blank spaces on his periodic table? did later discoveries justify his predictions?

schepotkina [342]

Answer:

mendeleev left a space

Explanation:

so the periodic table can be organize

7 0

2 years ago

HELP PLEASE!!!!

Olegator [25]

Answer:

#4. 32.06

#5. 10.90

Explanation:

I don't if 5 is completely correct, but number 4 should be correct.

6 0

3 years ago

Chem Stoichiometry, questions in Pic Thanks )