Which statement correctly describes an atom of the element helium

How to memorize the periodic table

viktelen [127]

You could break down the periodic table and learn each groups or practice writing each groups in different colors.

8 0

4 years ago

Q2 Write the following measurements in scientific notation using the concept of significant figures.

valentina_108 [34]

Answer:

Explanation:

i = 7.58 × 10 to the -4 power

j = 4.573 × 10 to the sixth power

k = 3.438 × 10 to the -2 power

h = 5 × 10 to the third power

hope this helps!

3 0

3 years ago

Use stoichiometry to calculate the following questions 1) Plants utilize light energy in the photosynthesis process to synthesiz

IceJOKER [234]

Answer:

Explanation:

Problem 1:

Plants utilize light energy in the photosynthesis process to synthesize glucose, C₆H₁₂O₆, from CO₂ and H₂O by way of the reaction 6CO₂ +6H₂O → C₆H₁₂O₆ +60₂. How many grams of CO₂ are consumed in the production of 90 g of glucose?

Given parameters:

Mass of glucose = 10g

Unkown:

Mass of CO₂ consumed = ?

Solution:

The reaction equation is given as:

6CO₂ + 6H₂O → C₆H₁₂O₆ +60₂

To solve this problem, the mole concept is a good approach. First work from the known to the unkown. The known is the given parameter which is the mass of glucose.

Using the mass of glucose, estimate its number of moles and compare to that of the unknown carbon dioxide gas.

Then find the mass from the obtained number of moles.

##

Number of moles of C₆H₁₂O₆ = $\frac{mass of C₆H₁₂O₆}{molar mass of C₆H₁₂O₆}$

given that atomic weight of:

C = 12.01g/mol

H = 1.01g/mol

O = 16.00g/mol

Molar mass of C₆H₁₂O₆ = (6 x 12.01) + (12 x 1.01) + (6 x 16) = 180g/mol

Number of moles = $\frac{90}{180}$ = 0.5mol

##

from the reaction equation,

1 mole of glucose is formed from 6 moles of CO₂

0.5 mole of glucose would be formed from (6 x 0.5)mole = 3moles

##

mass of CO₂ = number of moles x molar mass

molar mass of CO₂ = 12 + 2(16) = 44g/mol

mass of CO₂ = 3 x 44 = 132g of CO₂

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Problem 2:

For the reaction of 100.0 g of NaOH with Cl₂, 2NaOH + Cl₂ → NaClO + NaCI +H₂O, give the masses of each of the products.

Given parameters:

Mass of NaOH = 100g

Unknown:

mass of NaClo = ?

mass of NaCl = ?

mass of H₂O = ?

Solution:

Use the same procedure as highlighted in problem 1:

equation of reaction:

2NaOH + Cl₂ → NaClO + NaCI +H₂O

##

Number of moles of NaOH = $\frac{mass of NaOH}{molar mass of NaOH}$

Molar mass of NaOH:

Atomic weight of Na = 23g/mol

Atomic weight of O = 16g/mol

Atomic weight of H = 1g/mol

Molar mass of NaOH = 23 + 16 + 1 = 40g/mol

Number of moles of NaOH = $\frac{100}{40}$ = 2.5mole

##

From the equation;

first product NaClO:

2 moles of NaOH produced 1 mole of NaClO

2.5 moles of NaOH will produce $\frac{2.5}{2}$ mole = 1.25mole of NaClO

mass of NaClO = number of moles x molar mass

molar mass of NaClO = 23 + 35.5 + 16 = 74.5g/mol

mass of NaClO = 1.25 x 74.5 = 93.13g of NaClO

Second product NaCl:

2 moles of NaOH produced 1 mole of NaCl

2.5 mole of NaOH will produce 1.25 mole of NaCl

mass of NaCl = number of moles x molar mass

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

mass of NaCl = 1.25 x 58.5 = 73.13g of NaCl

Third product H₂O:

2 moles of H₂O produced 1 mole of H₂O

2.5 mole of H₂O will produce 1.25 mole of H₂O

mass of H₂O = number of moles x molar mass

molar mass of H₂O = 2(1) + 16 = 18g/mol

mass of H₂O = 1.25 x 18 = 22.5g of H₂O

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Hydrochloric acid (HCl gas dissolved in water) reacts with calcium carbonate in piece of limestone as follows: CaCO₃ + 2HCI → CaCl₂ + CO₂ + H₂0. If 14.6 g of CO₂ are produced in this reaction, what is the total mass of reactants and the total mass of the products?

Given parameters:

Mass of CO₂ = 14.6g

Unkown:

Total mass of products = ?

Total mass of reactants =?

Solution:

Total mass of products = mass of CaCl₂ + mass of CO₂ + mass of H₂O

Total mas of reactants = mass of CaCO₃ + mass of HCl

Using the procedures highlighted in the first problem, solve for the number of moles of the known:

##

Number of moles of CO₂ = $\frac{mass }{molar mass }$

molar mass of CO₂ = 12 + 2(16) = 44g/mol

Number of moles of CO₂ = $\frac{14.6}{44}$ = 0.33mole

##

number of moles of all species:

These species are in a ratio of one to one and the will have the same number of moles as that of the known:

Number of moles of CaCl₂ = 0.33mole

Number of moles of H₂O = 0.33mole

Number of moles of CaCO₃ = 0.33mole

For HCl:

1 mole of CO₂ is produced from 2 moles of HCl

0.33 mole of CO₂ will produce 2 x 0.33moles = 0.66moles of HCl

##

Mass of each species:

Mass = number of moles x molar mass

molar mass of CaCl₂ = 40 + 2(35.5) = 111g/mol

molar mass of H₂O = 2(1 ) + 16 = 18g/mol

molar mass of CaCO₃ = 40 + 12 + 3(16) = 100g/mol

molar mass of HCl = 1 + 35.5 = 36.5g/mol

mass of CaCl₂ = 0.33 x 111 = 36.83g

mass of H₂O = 0.33 x 18 = 5.94g

mass of CaCO₃ = 0.33 x 100 = 33g

mass of HCl = 0.66 x 36.5 = 24.09g

##

Total mass of reactants = 33g + 24.09g = 57.1g

Total mass of products = 36.83g + 14.6g + 5.94g = 57.3g

6 0

3 years ago

The way in which light moves through objects is related to the type of material from which the object is made

adelina 88 [10]

Answer: True

Explanation:

The speed of light in a material medium depends on its molecular structure, in particular its electromagnetic properties, electrical and magnetic permeability. These properties may have different values for different wavelengths or frequencies of the incident light.

In this way, the speed of light depends on the medium and reaches its maximum value in a vacuum, so that, it will be lower in a material medium . In the vacuum (or in the air) the speed of light is 3 x 10⁸ m / s and in any other medium its value is lower.

To characterize the particularities of the propagation of light in the media, the refractive index is introduced ,

n = c / v

where c is speed of light in a vacuum and v is the speed of light in the medium considered . So the speed of light in a medium is given by the refractive index whose value is always greater than 1.

6 0

4 years ago

A balloon is filled with 30L of helium gas at 1atm.What is the volume when balloon rises to an attitude where the pressure is on

Harrizon [31]

Answer:

$V_2=120L$