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DanielleElmas [232]
2 years ago
13

Can you tell me about atoms

Chemistry
1 answer:
trasher [3.6K]2 years ago
4 0

Answer:

is the smallest unit of ordinary matter that forms a chemical element.

Explanation:

and were created after the Big Bang 13.7 billion years ago.

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What is the concentration if 20 grams of NaOH was dissolved in enough water to make a 250 mL NaOH solution?
gizmo_the_mogwai [7]

Answer: 1 molar NaOH contains 40 grams of NaOH per every liter of water

Explanation:

so 2 M NaOH contains twice that amount, ie. 80 grams per liter. Then, ine 250 ml of weater, there should be 80/4 = 20 grams of solid NaOH dissolved.

3 0
3 years ago
Question 43 please. i’m not sure if i got the right answer
hram777 [196]

a) The reaction is exothermic since the overall enthalpy change is negative. this means that the system has lost energy to the environment, namely, the apparatus and due to drought.

b) We first calculate the number of moles in 3.55 grams of magnesium.

number of moles= mass/ atomic mass

                            =3.55/24

                            =0.1479 moles(to 4sf)

now, if 2 moles of magnesium give -1204kJ

        How much energy is given by 0.1479 moles

       = (0.1479×-1204kJ)

        =-89.0358kJ (don't forget the negative sign)

c) two molesof MgO produces -1204kJ of energy

then -234kJ will be produced by

=(-234kJ×2moles)/1204kJ

=0.3887moles

one mole of MgO weighs 24+16=40

therefore the mass produced is 0.3887moles×40=15.548grams

(d) we first find the number of moles of MgO in 40.3 grams

number of moles=mass/RFM

=40.3g/40= 1.0075moles

if 2 moles of MgO give 1204 kJ then decomposing 1.0075 moles requires

(1.0075 moles×1204kJ)/2=606.515kJ

4 0
3 years ago
A gaseous mixture contains 5.0 moles of nitrogen and 10.0 moles of helium . What is the total pressure if the temperature is 25
jolli1 [7]

Answer:

A) 122 atm

Explanation:

PV = nRT

Solve for P --> P = nRT/V

n = 10.0 mol + 5.0 mol = 15.0 mol

R = 0.08206 L atm / mol K

T = 25 + 273 = 298 K

V = 3.0

P = (15.0)(0.08206)(298) / (3.0) = 122 atm

6 0
2 years ago
Given that the density of gold and sand are 19. 3 g/cm^3 and 2. 95 g/cm^3, respectively, and that the density of the mixture is
SOVA2 [1]

The percent by mass of gold in the mixture will be 34.5%.

How to calculate the percentage?

The following information can be deduced based on the information given:

Density of gold = 19.3 g/cm³.

Density of sand = 2.94 g/cm³

Density of mixture = 4.17 g/cm³

It should be noted that when we find the volume fo gold on a 1cm³ sample, then we can be able to find that mass. The volume of gold will be calculated thus:

4.17 = [(19.3x + 2.95(1 - x)]

4.17 = 19.3x + 2.95 - 2.95x

4.17 = 16.35x + 2.95

x = 0.0746cm³

The mass of gold will be:

= 0.0746 × 19.3

= 1.44

The percent by mass of gold in the mixture will be:

= 1.44/4.17 × 100

= 34.5%

In conclusion, the percent by mass of gold in the mixture will be 34.5%.

What is Mass?

Mass is a physical body's total amount of matter. It also serves as a gauge for the body's inertia, or resistance to acceleration (change in velocity) in the presence of a net force. The strength of an object's gravitational pull to other bodies is also influenced by its mass.

The kilogram is the primary mass unit in the SI (kg). Even though weight is frequently measured using a spring scale rather than a balancing scale and directly compared with known masses, mass is not the same as weight in physics. Due to the lower gravity on the Moon, an object would weigh less than it does on Earth while maintaining the same mass. Given that weight is a force.

To learn more about  mass equation visit here:

brainly.com/question/19600926?referrer=searchResults

#SPJ4

3 0
1 year ago
Which of the following elements possesses an expanded octet?
stepan [7]
I think xe possess expanded octet
8 0
3 years ago
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