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3 years ago

Which of these has the most covalent character? NaF Caf2 Bef2 CsF SrF2

Chemistry

1 answer:

Ksenya-84 [330]3 years ago

3 0

Thus BeF2 is of most covalent character.

Anyways, covalent/ionic character is a bit tricky to figure out; we measure the difference in electronegativity of two elements bonding together and we use the following rule of thumb: if the charge is 0 (or a little more), the bond is non-polar covalent; if the charge is > 0 but < 2.0 (some references say 1.7), the bond is polar covalent; if the charge is > 2.0 then the bond is ionic. Covalent character refers to smaller electronegativity difference while ionic character refers to greater electronegativity difference.

Now, notice all of our bonds are with F, fluorine, which has the highest electronegativity of 3.98. This means that to determine character we need to consider the electronegativities of the other elements -- whichever has the greatest electronegativity has the least difference and most covalent character.
Na, sodium, has electronegativity of 0.93, so our difference is ~3 -- meaning our bond is ionic. Ca, calcium, has 1.00, leaving our difference to again be ~3 and therefore the bond is ionic. Be, beryllium, has 1.57 yielding a difference of ~2.5, meaning we're still dealing with ionic bond. Cs, cesium, has 0.79, meaning our difference is again ~3 and therefore again our compound is of ionic bond. Lastly, we have Sr, strontium, with an electronegativity of 0.95 and therefore again a difference of roughly 3 and an ionic bond.

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The mass fractions of a mixture of gases are 15 percent nitrogen, 5 percent helium, 60 percent methane, and 20 percent ethane wi

Setler79 [48]

Answer:

Explanation:

mass fraction N₂ : He : CH₄ : C₂H₆ : : 15 : 5 : 60 : 20

mole fraction N₂ : He : CH₄ : C₂H₆ : : 15/28 : 5/4 : 60/16 : 20/30

mole fraction N₂ : He : CH₄ : C₂H₆ : : .5357 : 1.25 : 3.75 : .67

Total mole fractions = .5357 + 1.25 + 3.75 + 0.67 = 6.2057

mole fraction of N₂ = .5357 / 6.2057 = .0877

mole fraction of He = 1.25 / 6.2057 = .20

mole fraction of CH₄ = 3.75 / 6.2057 = .6043

mole fraction of C₂H₆ = .67 / 6.2057 = .108

Partial pressure = total pressure x mole fraction

Partial pressure of N₂ = 1200 kPa x .0877 = 105.24 kPa

Partial pressure of He = 1200 kPa x .20 = 240 kPa

Partial pressure of CH₄ = 1200 kPa x .6043 = 725.16 kPa

Partial pressure of C₂H₆ = 1200 kPa x .108 = 129.6 kPa

6 0

3 years ago

How are DNA, genes and chromosomes related

zysi [14]

Chromosomes have genes, and genes are segments of DNA.

3 0

3 years ago

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A piece of unknown metal weighs 348g. When the metal piece absorbs 6.64kj of heat , its temperature increases from 24.4C to 43.6

Morgarella [4.7K]

Answer:

This metal could be the aluminium with a specific heat of $H = 993 \frac{J}{kgC}$

Explanation:

A pie of unknown metal presents a mass (M) of 348 g. This metal is heated using energy (E) of 6.64 kJ and the temperature increases from T1 =24.4 to T2 =43.6°C. We can calculate the specific heat (H) of this metal as follows

$H = \frac{E}{M*(T2-T1)}$

We can replace previously presented data in this equation. After simplifying and converting to adequated units, we found that

$H = \frac{6640 J}{0.348 Kg*(43.6-24.4) C} =\frac{6640 J}{6.686 KgC}$

Finally, the specific heat of this metal is

$H = 993 \frac{J}{kgC}$

The aluminium could be the metal, its specific heat is similar to that found in this problem.

Finally, we can conclude that this metal could be the aluminium with a specific heat of $H = 993 \frac{J}{kgC}$

7 0

3 years ago

For the reaction shown, calculate how many grams of oxygen form when each quantity of reactant completely reacts.

Diano4ka-milaya [45]

The balanced chemical reaction is given as follows:

2 KClO3(s) → 2 KCl(s) + 3 O2(g)

The starting amount of the reactant are given above. These values would be used for the calculations. We do as follows:

2.72 g KClO3 (1 mol / 122.50g )( 3 mol O2 / 2 mol KClO3 ) ( 32 g O2 / 1 mol O2 ) = 1.06 g O2

0.361 g KClO3 (1 mol / 122.50g )( 3 mol O2 / 2 mol KClO3 ) ( 32 g O2 / 1 mol O2 ) = 0.14 g O2

83.6 kg KClO3 (1000g / 1kg) (1 mol / 122.50g )( 3 mol O2 / 2 mol KClO3 ) ( 32 g O2 / 1 mol O2 ) = 3275.76 g O2

22.5 mg KClO3 (1 g / 1000 mg) (1 mol / 122.50g )( 3 mol O2 / 2 mol KClO3 ) ( 32 g O2 / 1 mol O2 ) = 0.009 g O2

4 0

3 years ago

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One radioactive isotope of calcium has an atomic mass of 47,how many neutrons are in the calcium -47 nucleus

jekas [21]

Answer: 27 neutrons

Explanation:

Recall that the number of protons in the nucleus of an atom = Atomic number.

Hence, Calcium with mass number 47 and atomic number 20 will have 20 protons

Therefore, since Mass number = number of protons + neutrons

47 = 20 + neutrons

Neutrons = 47 - 20 = 27

Thus, there are 27 neutrons in radioactive calcium nucleus.

6 0

4 years ago