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Sholpan [36]
1 year ago
14

Dominic and Eva are using the same type of stopwatches to measure the time it takes for a chemical reaction to occur. They each

use the same stopwatch to measure the time. These are their results:
Person Trial 1
Dominic 78 seconds
Eva 81 seconds

Why are their results unreliable and can lead to a pseudoscientific claim?
They did not repeat their tests multiple times.

They used the same type of stopwatch.

They did not change the reactants in their chemical reactions.

Only one person should have collected the data.
Chemistry
1 answer:
SIZIF [17.4K]1 year ago
4 0
They did not repeat their tests multiple times.

Reason being is using the same stopwatch doesn’t matter and changing the reactants won’t help, and you without a doubt need more than one person collecting the data so,

They did not repeat their tests multiple times is the answer.
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When Mendeleev started his work on organizing the elements, about how many had
Talja [164]

Answer:

About 60.

Explanation:

Mendeleev knew of 63 elements. He wrote their properties on cards and arranged them in order of atomic mass.

That's how he discovered that the properties of elements are periodic functions of their atomic masses.

8 0
3 years ago
Can be used to help an individual with an eating disorder learn better ways to cope with stress an
baherus [9]

Answer: Psychotherapy

Explanation:

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7 0
3 years ago
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mixture of N 2 And H2 Gases weighs 13.22 g and occupies a volume of 24.62 L at 300 K and 1.00 atm.Calculate the mass percent of
anygoal [31]

<u>Answer:</u> The mass percent of nitrogen gas and hydrogen gas is 91.41 % and 8.59 % respectively.

<u>Explanation:</u>

To calculate the number of moles, we use the equation given by ideal gas equation:

PV = nRT

where,

P = Pressure of the gaseous mixture = 1.00 atm

V = Volume of the gaseous mixture = 24.62 L

n = number of moles of the gaseous mixture = ?

R = Gas constant = 0.0821\text{ L atm }mol^{-1}K^{-1}

T = Temperature of the gaseous mixture = 300 K

Putting values in above equation, we get:

1.00atm\times 24.62L=n_{mix}\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 300K\\\\n_{mix}=\frac{1.00\times 24.62}{0.0821\times 300}=0.9996mol

We are given:

Total mass of the mixture = 13.22 grams

Let the mass of nitrogen gas be 'x' grams and that of hydrogen gas be '(13.22 - x)' grams

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

<u>For nitrogen gas:</u>

Molar mass of nitrogen gas = 28 g/mol

\text{Moles of nitrogen gas}=\frac{x}{28}mol

<u>For hydrogen gas:</u>

Molar mass of hydrogen gas = 2 g/mol

\text{Moles of hydrogen gas}=\frac{(13.22-x)}{2}mol

Equating the moles of the individual gases to the moles of mixture:

0.9996=\frac{x}{28}+\frac{(13.22-x)}{2}\\\\x=12.084g

To calculate the mass percentage of substance in mixture we use the equation:

\text{Mass percent of substance}=\frac{\text{Mass of substance}}{\text{Mass of mixture}}\times 100

Mass of the mixture = 13.22 g

  • <u>For nitrogen gas:</u>

Mass of nitrogen gas = x = 12.084 g

Putting values in above equation, we get:

\text{Mass percent of nitrogen gas}=\frac{12.084g}{13.22g}\times 100=91.41\%

  • <u>For hydrogen gas:</u>

Mass of hydrogen gas = (13.22 - x) = (13.22 - 12.084) g = 1.136 g

Putting values in above equation, we get:

\text{Mass percent of hydrogen gas}=\frac{1.136g}{13.22g}\times 100=8.59\%

Hence, the mass percent of nitrogen gas and hydrogen gas is 91.41 % and 8.59 % respectively.

5 0
3 years ago
Estradiol is a female sexual hormone that causes maturation and maintenance of the female reproductive system. Elemental analysi
Ipatiy [6.2K]

Answer:

The molecular formula of estradiol is: C_{18}H_{24}O_2.

Explanation:

Molar mass of of estradiol = M= 272.37 g/mol

Let the molecular formula of estradiol be C_xH_yO_z

Percentage of an element in a compound:

\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{molecular mass of element}}\times 100

Percentage of carbon in estradiol  :

\frac{x\times 12 g/mol}{272.37 g/mol}\times 100=79.37\%

x = 18.0

Percentage of hydrogen in estradiol  :

\frac{y\times 1g/mol}{272.37 g/mol}\times 100=8.88\%

y = 24.2 ≈ 24

Percentage of oxygen in estradiol  :

\frac{z\times 16 g/mol}{272.37 g/mol}\times 100=11.75\%

z = 2

The molecular formula of estradiol is: C_xH_yO_z:C_{18}H_{24}O_2

7 0
3 years ago
If an atom has 12 protons 12 neutrons, and 12 electrons, what is the charge of the atom?
Evgesh-ka [11]
I think the charge is +2
Hope this helps
6 0
2 years ago
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