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Multiple Questions, Brainliest and 98 points to whoever answers all questions correctly

otez555 [7]

Question 1

The average atomic mass of element is 84.66

calculation

Average atomic mass is of an element is the sum of masses of its isotope each multiplied by its natural abundance.

that is.

[(50.50 x 83.75) /100] + [( 30.25 x 84.45)/100] + [(,9.25 x 87.40)/100]

= 42.29 +25.55 +16.82= 84.66

Question 2

fill the table

symbol element protons neutrons Electrons mass No Atomic No

Cs-133 cesium 55 78 55 133 55

Na-23 sodium 11 12 11 23 11

Ne 22 Neon 10 12 1 0 22 10

Au -197 Gold 79 118 79 197 79

Question 3

The moles of tungsten that are in 93.50 grams are 0.509 moles

moles= mass/molar mass

molar mass of tungsten = 183.84 g/mol

moles is therefore= 93.50 g/ 183.84 g/mol= 0.509 moles

question 4

CO2 molecules at STP are 1.547 x10^23 molecules

Step 1: find the moles of CO2

At STP 1 mole of a gas= 22.4 l

? =5.75 L

by cross multiplication

= (5.75 L x 1 mole)/ 22.4 L= 0.257 moles

Step 2: use the Avogadro's constant to calculate the number of molecule

that is 1 moles = 6.02 x10^23 molecules

0.257 moles= ? molecules

by cross multiplication

=(0.257 moles x 6.02 x 10^23) / 1 mole = 1.547 x10^23 molecules

question 5

The number of calcium atoms is 3.82 x10^24 atoms

Step 1: find the moles of calcium

= 253.50 g /40 g/mol= 6.34 moles

Step 2: use the Avogadro's law to calculate the number of atoms.

that is 1 mole= 6.02 x 10^23 atoms

6.34 moles= ? atoms

=6.34 x 6.02 x10^23 = 3.82 x10^24 atoms

Question 6

mass in grams of NiBr2 is 126.97 grams

Step 1: by use of Avogadro's law constant calculate the number of moles

that is 1 mole = 6.02 x 10^23

? = 3.50 x 10^23

by cross multiplication

= (1 mole x 3.50 x10^23) / 6.02 x10^23 =0.581 moles

step 2: calculate the mass

mass =moles x molar mass

= 0.581 moles x218.53 g/mol = 126.97 grams

Bonus question

The molecules of water= 1.00 x10^26 molecules

calculation

convert liters into ml

= 3 x 1000 = 3000 ml

find the mass of water

= density x volume

=3000 x0.998 2994 grams

find the moles of water=mass/molar mass

= 2994 g/ 18 g/mol= 166.33 moles

Use Avogadro's constant to calculate the molecules of water

that is 1 mole= 6.02 x10^23 molecules

166.33 moles= ? molecules

= (166.33 moles x6.02 x10^23 molecules) / 1 mole = 1.00 x10^26 molecules

3 0

3 years ago

Read 2 more answers

Help!!!

Mrac [35]

Answer:

Explanation:

Atomic mass is based on a relative scale and the mass of 12C

(carbon twelve) is defined as 12 amu; so, this is an exact number.

Why do we specify 12C? We do not simply state that the mass of a C atom is

12 AMU because elements exist as a variety of isotopes.

Carbon exists as two major isotopes, 12C, and 13C ( 14C exists and has

a half life of 5730 y, 10C and 11C also exist and their half lives are

19.45 min and 20.3 days respectively). Each carbon atom has the

same number of protons and electrons, 6. 12C has 6 neutrons, 13C has

7 neutrons, and 14C has 8 neutrons and so on. So, we must specify

which C atom defines the scale.

All the masses of the elements are determined relative to 12C.

Average Atomic Mass

Since many elements have a number of isotopes, chemists use average

atomic mass. On the periodic table the mass of carbon is reported as

12.011 amu. No single carbon atom has a mass of 12.011, but in a handful

of C atoms the average mass of a carbon atom is 12.011.

Why 12.011?

If a sample of carbon was placed in a mass spectrometer the

spectrometer would detect two different C atoms, 12C and 13C.

The natural abundance of 14C, 10C and 11C in geologic (i.e. old) samples is so low that we cannot

detect the effect these isotopes have on the average mass.

From the information collected from the mass spectrometer the average

mass of a carbon atom is calculated.

The mass of 12C is, of course, 12 amu.

13C is 1.0836129 times heavier than 12C; so, the mass of 13C is 13.003355

24

amu.

98.89% of the sample is 12C, and

1.11% of the sample is 13C

4 0

3 years ago

Can one mole of peas fit inside your house? List the materials and steps of an experiment that answers the

svlad2 [7]

Answer:

No.

Explanation:

No, one mole of peas do not fit inside a house because one mole is equals to 6.022 × 10²³ units which is a very large value. mole only use for atoms, ions and molecules etc due to very small size but mole is not used for big sized materials such as peas and other vegetables etc. So that's why we can conclude that one mole of peas did not fit inside a house.

6 0

3 years ago

1) How many moles of gas occupy 58 L at a pressure of 2.2 atmospheres and a temperature

Sergio039 [100]

Here, we need to solve this problem using Ideal gas law ( PV=nRT).

Where –

P = Pressure in atm
V = Volume in L
n = moles
R = Ideal gas law constant
T = Temperature in K

Now, according to the question –

V = 58 L
P = 2.2 atm
T = 313 K
R = 0.0821 atm L/ mol K

Calculation –

$\qquad$ $\pink{\twoheadrightarrow\bf PV = nRT}$

$\qquad$ $\twoheadrightarrow\sf n = \dfrac{PV}{RT}$

$\qquad$ $\twoheadrightarrow\sf n = \dfrac{ 2.2 \: \:\times 58 \: } {0.0821 \times 313}$

$\qquad$ $\twoheadrightarrow\sf n = \dfrac{ 2.2 \times 58}{0.0821 \times 313}$

$\qquad$ $\twoheadrightarrow\sf n =\dfrac{127.6}{25.7}$

$\qquad$ $\pink{\twoheadrightarrow\bf n = 4.9656 \: moles }$

_______________________________________

8 0

3 years ago

Read 2 more answers

Exactly 12.0 grams of potassium chlorate is placed in a reaction vessel; following the decomposition, 1.55g of kClO3- remain unr

Damm [24]

Answer:

3.3L

Explanation:

Firstly, we write the reaction equation :

2KClO3 ——-> 2KCl + 3O2

Now we need to know the mass of potassium chlorate reacted = total mass - mass of unreacted chlorate

= 12.0 - 1.55 = 10.45g

Now we need to know the number of moles of chlorate reacted. This equals the mass reacted divided by the molar mass.

The molar mass of potassium chlorate = 39 + 35.5 + 3(16) = 122.5g/mol

The number of moles = 10.45/122.5= 0.0853moles.

From the reaction equation, we know that 2 moles of chlorate yielded 3 moles of oxygen. The number of moles of oxygen produced from 0.0853moles chlorate is thus = 0.12795moles

Now, to calculate the total volume of oxygen collected, we use the ideal gas equation.

Here PV = nRT

hence, V = nRT/P

We have the following values: P = 0.95atm

If 1 atm = 101,325Pa, 0.95atm = 101325 * 0.95 = 96258.75Pa

T = 25 degrees Celsius = 25 + 273.15 = 298.15K

n = 0.12795 moles

R = molar gas constant = 8314.462L.Pa/K.mol

Putting these values into the equation: V = (0.12795 * 8314.462 * 298.15)/ 96,258.75 = 3.3L

3 0

3 years ago