Answer:
2.01
Explanation:
First, let's convert grams to moles
(Na) 22.99 + (F) 18.998 = 41.988
Every mole of NaF is 41.988 grams
21/41.988 = 0.500143 moles of NaF
For every Cr+3, we will need 2 NaF, so Cr+3 will be half of NaF
0.500143/2 = 0.250071
molarity = moles/liters
0.250071/0.125 = 2.0057 M
Answer is: -601,2 kJ/mol
Chemical reaction: Mg(OH)₂ → MgO + H₂O.
ΔHrxn = 37,5 kJ/mol.
ΔHf(Mg(OH)₂) = <span>−924,5 kJ/mol.
</span>ΔHf(H₂O) = <span>−285,8 kJ/mol.
</span>ΔHrxn -enthalpy of reaction.
ΔHf - enthalpy of formation.
<span>ΔHrxn=∑productsΔHf−∑reactantsΔHf.
</span>ΔHf(MgO) = -924,5 kJ/mol - (-285,8 kJ/mol) + 37,5 kj/mol.
ΔHf(MgO) = -601,2 kJ/mol.
Na(s) forms an ionic bond.
<h3>What is ionic bond?</h3>
The main interaction in ionic compounds is ionic bonding, a type of chemical bonding that involves the electrostatic attraction between two atoms or ions with dramatically differing electronegativities. Along with metallic and covalent bonds, it is one of the most common types of bonds. Atoms (or collections of atoms) possessing an electrical charge are known as ions. Ions with negative charges are created when atoms gain electrons (called anions). Positively charged ions are produced when atoms lose electrons (called cations). In contrast to covalence, this electron transfer is referred to as electrovalence.
Ionic chemicals normally do not conduct electricity when solid, only when molten or in solution. Depending on the charge of the ions they are made of, ionic compounds typically have a high melting point.
To learn more about ionic bond from the given link:
brainly.com/question/13526463
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You can use P1V1/T1 = P2V2/T2 but since pressure is constant is becomes V1/T1=V2/T2
V1=0.5 L
T1=203 K
T2=273 K
V2=unknown
0.5L/203 = V2/273
V2= 0.67 L so C
Hope this helps :)
