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3 years ago

What is the general trend for valence electrons as you go across the periodic table left to right

1 answer:

6 0

The atomic radius decreases across a period from left to right and increases down a given group. The atoms with the largest atomic radii are located in group l and at the bottom of groups. Moving from left to right across a period, electrons are added one at a time to the outer energy shell. Hope this helps!

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How many moles are in 12.5 g ammonium chloride

77julia77 [94]

Answer:

0.233682161601125

Explanation:

3 0

2 years ago

While in Europe, if you drive 109 km per day, how much money would you spend on gas in one week if gas costs 1.10 euros per lite

MrRissso [65]

Answer:

The amount is $x = 113.3 \ dollars$

Explanation:

From the question we are told that

The distance traveled per day is $l = 109\ km = \frac{109}{1.609} = 67.74 \ mi$

The cost of one liter is $c = 1.10 \ euros/liter = 1.10 * 1.26 = 1.36 \ dollars/liter$

The car's gas mileage is $b = 22.0 \ mi/gal$

Generally the amount of distance covered in one week is evaluated as

$z = 67.74 * 7$

$z = 474.18 \ mi$

The amount of gas used in one week by the car is mathematically represented as

$k = \frac{ z}{ b}$

=> $k = \frac{ 474.18}{ 22}$

=> $k = 22 \ gal$

converting to liters

$k = 22 * 3.78541=83.28 \ liters$

Thus the amount spent on gas in one week is

$x = k * c$

=> $x = 83.28 * 1.36$

=> $x = 113.3 \ dollars$

5 0

3 years ago

Vocabulary

mihalych1998 [28]

Answer:

the only one i really know is magna carta which is an article created so that the king's power could be limited or something

6 0

3 years ago

Find the enthalpy change per mole of sodium when sodium reacts with water. 13 grams of sodium reacts with 247 cm3 of water, prod

Ierofanga [76]

The answer is

-79 kJ/mol

The explanation:

The reaction equation is:

2Na + 2H2O  2NaOH + H2

when ΔHrxn= -q

and q=cmΔT

where:

-q is amount of heat absorbed/released

-and c is specific heat of solution (in such calculation an assumption is made that c solution = c water)

- and m is mass of solution

- and ΔT is temperature change

1- now we need to Find mass of solution:

m solution = m(H2O)+ m(Na)-m(H2)m(H2O)

m H2O= V(H2O)*ρ(H2O)

= 247 cm3*1g/cm3 = 247 gm

and m(Na)= 13 g

2- now we need to Find m(H2):

n(Na)(moles Na)= mass/Molar mass = 13g/23 g/mol = 0.57 mol.

According to equation mole ratio n(Na):n(H2)= 2:1,

then n(H2)=n(Na)/2

=0.57/2=0.29 mol.

∴m(H2)= moles * molar mass

=0.29 mol *2g/mol

= 0.58 g

∴m solution= 247 g + 13 g – 0.58 g = 259.42 g

and when q=4.18 J/K g* 259.42 g *(339.7 K – 298 K)= 45218 J

The temperature of solution increased because heat was absorbed by the solution (q>0).

Then ΔHrxn= -q = -45218 J per 0.57 mol of Na

3- now we need to Find ΔHrxn per 1 mole of Na

ΔHrxn = -45218J/0.57 mol = -79331 J/mol ≈ -79 kJ/mol

4 0

2 years ago

Read 2 more answers

The solubility of a gas is 0.890 g/L at a pressure of 120 kPa. What is the solubility of the gas if the pressure is changed to 1

IgorC [24]

The solubility of the gas if the pressure is changed to 100 kPa is 0.742 g/L

<h3>Effect of Pressure on Solubility </h3>

As the <em>pressure </em>of a gas increases, the <em>solubility </em>increases, and as the <em>pressure </em>of a gas decreases, the <em>solubility </em>decreases.

Thus, Solubility varies directly with Pressure

If S represents Solubility and P represents Pressure,

Then we can write that

S ∝ P

Introducing proportionality constant, k

S = kP

S/P = k

∴ We can write that

$\frac{S_{1} }{P_{1} } = \frac{S_{2} }{P_{2} }$