All categories

2 years ago

Describe the contributions of 3 scientists to our current understanding of the atom

Chemistry

1 answer:

bogdanovich [222]2 years ago

8 0

Answer:

1. Rutherford did the scattering experiment and observed that some of the rays bounce back. He concluded that there is a mass in which positive charge is concentrated. This marks the discovery of nucleus.

2. J.J Thomson discovered electrons by conducting cathode ray experiment.

3. Dalton postulated that matter is made up of small particles caled atoms

You might be interested in

A 15.00-ml sample of a naoh solution of unknown concentration requires 17.88 ml of a 0.1053 m h2so4 solution to reach the equiva

Sergeu [11.5K]

Answer:

0.1255 M

Explanation:

1) Data:

Base: NaOH

Vb = 15.00 ml = 15.00 / 1,000 liter

Mb = ?

Acid: H₂SO₄

Va = 17.88 ml = 17.88 / 1,000 liter

Ma = 0.1053

2) Chemical reaction:

The titration is an acid-base (neutralization) reaction to yield a salt and water:

Acid + Base → Salt + Water

H₂SO₄ (aq) + NaOH(aq) → Na₂SO₄ (aq) + H₂O (l)

3) Balanced chemical equation:

H₂SO₄ (aq) + 2 NaOH(aq) → Na₂SO₄ (aq) + 2H₂O (l)

Placing coefficient 2 in front of NaOH and H₂O balances the equation

4) Stoichiometric mole ratio:

The coefficients of the balanced chemical equation show that 1 mole of H₂SO₄ react with 2 moles of NaOH. Hence, the mole ratio is:

1 mole H₂SO₄ : 2 mole NaOH

5) Calculations:

a) Molarity formula: M = n / V (in liter)

⇒ n = M × V

b) Nunber of moles of acid:

nₐ = Ma × Va = 0.1053 (17.88 / 1,000)

c) Number of moles of base, nb:

nb = Mb × Vb = Mb × (15.00 / 1,000)

d) At equivalence point number of moles of acid = number of moles of base

nₐ = nb

0.1053 × (17.88 / 1,000) = Mb × (15.00 / 1,000)

Mb = 0.1053 × 17.88 / 15.00 = 0.1255 mole/liter = 0.1255 M

3 0

3 years ago

Read 2 more answers

Our good friend and pseudo scientist, homer simpson, attempts to analyze 300 mg of an unknown compound containing only c and h b

iragen [17]

$C_{x}H_{y} + O_{2} --\ \textgreater \ x CO_{2} + \frac{y}{2} H{2}O

540mg H_{2}O* \frac{1 mmol H_{2}O}{18 mg H_{2}O} =30 mmol H_{2}O

\\ \\30 mmolH_{2}O -have - 60 mmol H
\\ \\ 60 mmol H* \frac{1mg H}{1 mmol H} =60 mg H
\\ \\300mg C_{x}H_{y} - 60 mg H= 240 mg C
\\ \\ 240 mgC* \frac{1mmol}{12mg} =20 mmol C

20 mmol C: 60 mmol H=1 mol C : 3 mol H

$

7 0

3 years ago

Help ASAP!!!!!!!!!!!!!!!!!!!!!!!!!

BartSMP [9]

Answer:

ok .

Explanation:

3 0

3 years ago

A sample of gas occupies a volume of 4.5 L at 20 Celsius. What volume will it occupy at -15 celsius, if the pressure remains con

nataly862011 [7]

Answer: 3.96L

Explanation:

PV = nRT

The way I like to do it, it's I get rid of whatever I do not need.

We have to do an equation for sure to make both sides equal and find our desired result.

The pressure is constant, so it would be constant in both sides, therefore, there is no point in using it.

The R is a constant used in both sides so there is no point on using it either.

We don't need to work with moles in this case, so let's forget about the moles.

Therefore we are left with only V (volume ) and T(Temperature)

Which would logically make this:

V1/T1 = V2/T2

T1/V1 = T2/V2

Both of these would work, we always use whatever makes our calculations easier without complicating our lives with the algebra.

That should remind you of Charles' Law

Transform degrees into kelvins

20 + 273.15 = 293.15K

-15 + 273.15 = 258.15K

So, 4.5L/293.15K = V2/258.15K

V2 = (4.5L/293.15K) x 258.15K

V2 = 3.96L

8 0

2 years ago

Predict whether each of the following molecules is polar or nonpolar? 1. XeF4 3. CCl4 5. CH3Br

denpristay [2]

The answer the following are as follows:

 1. XeF4 - molecules are polar

3. CCl4 - molecules are polar

5. CH3Br - molecules are non-polar

I hope my answer has come to your help. God bless and have a nice day ahead!

5 0

3 years ago