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3 years ago

Element X has two isotopes. The table gives information about these isotopes.

Chemistry

1 answer:

UNO [17]3 years ago

5 0

Answer: The average atomic mass of element X is 63.545 amu.

Explanation:

The average atomic mass is can be calculated by the summation of the product of the atomic mass of each isotope multiplied by its abundance (abundance % / 100.0)

Element X has two isotopes:

1) At.mass = 62.9296 amu and its abundance = 0.6915

2) At.mass = 64.9278 amu and its abundance = 0.3085

The average atomic mass of element X = (62.9296 amu)*(0.6915) + (64.9278 amu)*(0.3085) = 63.454 amu

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A sample of oxygen gas at a pressure of 1.19 atm and a temperature of 24.4 °C, occupies a volume of 18.7 liters. If the gas is a

mihalych1998 [28]

Answer:

$\boxed {\boxed {\sf 0.757 \ atm}}$

Explanation:

We are asked to find the pressure of a gas given a change in volume. Since the temperature remains constant, we are only concerned with volume and pressure. We will use Boyle's Law, which states the volume is inversely proportional to the pressure. The formula for this law is:

$P_1V_1= P_2V_2$

Initially, the oxygen gas occupies a volume of 18.7 liters at a pressure of 1.19 atmospheres.

$1.19 \ atm * 18.7 \ L = P_2V_2$

The gas expands to a volume of 29.4 liters, but the pressure is unknown.

$1.19 \ atm * 18.7 \ L = P_2 * 29.4 \ L$

We are solving for the new pressure, so we must isolate the variable $P_2$ . It is being multiplied by 29.4 liters. The inverse operation of multiplication is division. Divide both sides of the equation by 29.4 L.

$\frac {1.19 \ atm * 18.7 \ L}{29.4 \ L} =\frac{ P_2 * 29.4 \ L}{29.4 \ L}$

$\frac {1.19 \ atm * 18.7 \ L}{29.4 \ L} =P_2$

The units of liters cancel.

$\frac {1.19 \ atm * 18.7 }{29.4 } =P_2$

$\frac {22.253}{29.4 } \ atm = P_2$

$0.7569047619 \ atm =P_2$

The original measurements all have 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place. The 9 in the ten-thousandth place to the right of this place tells us to round the 6 up to a 7.

$0.757 \ atm \approx P_2$

The pressure of the gas sample is approximately 0.757 atmospheres.

3 0

3 years ago

Read 2 more answers

What is the oxidation state of phosphorus in the following compounds?

Korolek [52]

A) H3PO4
H(+1),
P(X)
O(-2)
3*(+1)+x+4*(-2)=0, 3+x-8=0, x=+5
b)P2O5
P(x)
O(-2)
2x-2*5=0, 2x=10, x=+5
c) PH3
P(x)
H(+1)
x+3*(+1)=0, x+3=0, x=-3

5 0

4 years ago

Question 1(Multiple Choice Worth 3 points)

Bingel [31]

1) Answer:

moles of oxygen (n) = 1.86 moles

Explanation:

according to Boyle's law the formula to solve this problem is:

PV=nRt

when P is the pressure which equal 1.25 atm

and V is the volume which equal 37.5 L

n is the number of moles which we need to calculate it

R is constant which equal 0.082

t is the temperature in kelvin

By substitution:

1.25*37.5 = n * 0.082 * 307

So n = 1.86 moles

2) Answer:

the volume of oxygen gas = 34 L

Explanation:

at standard temperature and pressure (STP) 1 mole of gas will equal = 22.4L

So when we have 1.5 moles of oxygen at standard temperature and pressure (STP) so we will estimate it like that

1.5 moles *22.4 L/ 1 mole = approximately 34 L

3) Answer:

The volume of H2 = 2.29 L

Explanation:

according to the Balanced equation we can see that the molar ratio between Zn and H2 1 : 1

so to know the number of moles of H2 we will get it for Zn first :

number of moles Zn = mass of Zn / molar mass Zn

= 5.98 / 65.39 =0.0914 moles

so number of moles H2 = 0.09 moles

by substitution in the following formula:

PV = nRT

0.978 * V = 0.09 * 0.082 * 298

so The volume of H2 = 2.29 L

4) Answer:

Volume of O2 = 1.4 L

Explanation:

first we have to balance the equation:

2Na2O2 +2CO2 → 2Na2CO3 + O2

2 mole CO2 give 1 mole of O2 so the molar ratio is 2:1

at STP 1 mole of gas will equal = 22.4 L

??? moles of CO2 = 2.8

n CO2 = 0.125 moles so n O2 = 0.125 /2 = 0.0625 moles

so when 1 mole of as = 22.4

0.0625 moles O2 = ???

Volume of O2 =0.0625 moles * 22.4 L/ 1 mole

= 1.4 L

5) Answer:

the initial quantity of sodium metal used = 17.2 gram

Explanation:

at STP 1 mole of gas will equal = 22.4 L

so moles of H2 equal ?? when 8.40 liters of H2 gas were produced

so moles of H2 = 8.4/22.4 =0.375 moles

and according to the balanced equation the molar ratio between H2 ans Na is 1 : 2

so number of moles for Na = 0.375 *2 = 0.75 moles

to get the initial quantity of sodium metal (mass Na) = number of moles * molar mass

mass Na = 0.75 moles * 23 gm/mole= 17.25

6) Answer:

False

Explanation:

because STP means standard temperature and pressure. and the Standard temperature must be 273 K and the standard pressure must be 1 atm but in the question the temperature is 298 K not 273 K so , It is not a standard temperature

7) Answer:

22.4 liters

Explanation:

1 mole of gas will equal = 22.4 L

because at the Standard temperature must be 273 K and the standard pressure must be 1 atm

so V = nRT/P

=1 mole * 0.082 * 273 K / 1 aTm

= 22.4 liters

4 0

4 years ago

Which of the following is a strong base? a. h2o b. NH3 c.CaCo3 d. NaOh

hichkok12 [17]

Answer:

d. naoh

Explanation:

4 0

3 years ago

A balloon of air now occupies 5.0 L, at 25 celcius and 1.00 atm. What temperature was it initially, if it occupied 4.0 L and was

xenn [34]

Answer: A. 219K

Explanation:

Using the Combined Gas Law; P1 V1/T1 = P2V2/T2

Where P1 = 0.92 atm, P2 = 1.00 atm

V1 =4.0 L, V2 = 5.0 L

T1 = ?, T2 = 25 celcius = 298K

We therefore make T1 the subject of the formular;

T1 = P1 . V1 .T2 / P2. V2

= 0.92atm x 4.0L x 298K / 1.00 atm x 5.0 L

= 1096.64 / 5

= 219.328 approx 219K

5 0

4 years ago