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4 years ago

Why is it important that scientific knowledge changes?

Chemistry

2 answers:

PSYCHO15rus [73]4 years ago

5 0

Answer:

Scientific knowledge can change because it is often examined and re-examined by new investigations and scientific argumentation but because of these frequent examinations, scientific knowledge becomes stronger, leading to its durability. Scientific knowledge is durable and robust, but open to change.

aleksandrvk [35]4 years ago

3 0

Answer:Scientific knowledge can change because it is often examined and re-examined by new investigations and scientific argumentation. Because of these frequent examinations, scientific knowledge becomes stronger, leading to its durability. ... B: Scientific knowledge is durable and robust, but open to change.

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One hundred million copper atoms are arranged in a line. Which is a reasonable estimate for the length of this line?

Anettt [7]

The size of an atom is roughly 10^-10 metres

10^-10 • 100,000,000 = 0.01 metres

Since 1 metre = 100 centimetre

0.01 x 100 = 1 centimetre

There’s your answer

8 0

3 years ago

What is the molar concentration of Pb+ in a solution that contains 6.73 ppm of

Katarina [22]

Answer:

2.03 × 10⁻⁵ M

Explanation:

Step 1: Given data

Concentration of Pb(NO₃)₂: 6.73 ppm = 6.73 mg/L

Step 2: Convert 6.73 mg/L to mol/L

The molar mass of 331.2 g/mol.

6.73 × 10⁻³ g/L × 1 mol/331.2 g = 2.03 × 10⁻⁵ mol/L = 2.03 × 10⁻⁵ M

Step 3: Calculate the molar concentration of Pb²⁺

Let's consider the ionization of Pb(NO₃)₂.

Pb(NO₃)₂(aq) ⇒ Pb²⁺(aq) + 2 NO₃⁻(aq)

The molar ratio of Pb(NO₃)₂ to Pb²⁺ is 1:1. The molar concentration of Pb²⁺ is 1/1 × 2.03 × 10⁻⁵ M = 2.03 × 10⁻⁵ M.

8 0

3 years ago

Convert 35 mL to cm3. 1 mL = 1 cm3

ivann1987 [24]

It’s still 35cm3
mark me brainliest

8 0

3 years ago

Chloral hydrate (C2H3Cl3O2) is a drug formerly used as a sedative and hypnotic.

Dmitrij [34]

Answer :

(a) The molar mass of $C_2H_3Cl_3O_2$ is, 165.5 g/mole

(b) The moles of $C_2H_3Cl_3O_2$ is, 3.02 moles

(c) The mass in grams of $2.0\times 10^{-2}$ mole chloral hydrate is, 3.31 g

(d) The number of chlorine atoms in 5.0 g chloral hydrate is, $5.4\times 10^{22}$

(e) The mass of chloral hydrate will be, 1.55 g

(f) The mass of exactly 500 molecules of chloral hydrate is, $1.99\times 10^{23}$

Explanation :

(a) To calculate the molar mass of chloral hydrate.

The formula of chloral hydrate is, $C_2H_3Cl_3O_2$

Atomic mass of carbon = 12 g/mole

Atomic mass of hydrogen = 1 g/mole

Atomic mass of oxygen = 16 g/mole

Atomic mass of chlorine = 35.5 g/mole

Now we have to determine the molar mass of chloral hydrate.

$\text{Molar mass of }C_2H_3Cl_3O_2$ =2(12g/mole)+3(1g/mole)+3(35.5g/mole)+2(16g/mole)=165.5g/mole[/tex]

The molar mass of $C_2H_3Cl_3O_2$ is, 165.5 g/mole

(b) Now we have to determine the moles of $C_2H_3Cl_3O_2$ .

$\text{Moles of }C_2H_3Cl_3O_2=\frac{\text{Mass of }C_2H_3Cl_3O_2}{\text{Molar mass of }C_2H_3Cl_3O_2}=\frac{500.0g}{165.5g/mole}=3.02moles$

The moles of $C_2H_3Cl_3O_2$ is, 3.02 moles

(c) Now we have to determine the mass in grams of $2.0\times 10^{-2}$ mole chloral hydrate.

$\text{Mass of }C_2H_3Cl_3O_2=\text{Moles of }C_2H_3Cl_3O_2\times \text{Molar mass of }C_2H_3Cl_3O_2$

$\text{Mass of }C_2H_3Cl_3O_2=(2.0\times 10^{-2}mole)\times (165.5g/mole)=3.31g$

The mass in grams of $2.0\times 10^{-2}$ mole chloral hydrate is, 3.31 g

(d) To calculate the number of chlorine atoms are in 5.0 g chloral hydrate.

First we have to determine the moles of $C_2H_3Cl_3O_2$ .

$\text{Moles of }C_2H_3Cl_3O_2=\frac{\text{Mass of }C_2H_3Cl_3O_2}{\text{Molar mass of }C_2H_3Cl_3O_2}=\frac{5g}{165.5g/mole}=0.03moles$

Now we have to calculate the number of chlorine atoms in chloral hydrate.

In $C_2H_3Cl_3O_2$ , there are, 2 carbon atoms, 3 hydrogen atoms, 3 chlorine atoms and 2 oxygen atoms.

As, 1 mole of $C_2H_3Cl_3O_2$ contains $3\times 6.022\times 10^{23}$ chlorine atoms

So, 0.03 mole of $C_2H_3Cl_3O_2$ contains $0.03\times 3\times 6.022\times 10^{23}=5.4\times 10^{22}$ chlorine atoms

The number of chlorine atoms in 5.0 g chloral hydrate is, $5.4\times 10^{22}$

(e) To calculate the mass of chloral hydrate would contain 1.0 g Cl.

As, $3\times 35.5g$ of chlorine present in 165.5 g of $C_2H_3Cl_3O_2$

So, 1 g of chlorine present in $\frac{165.5}{3\times 35.5}=1.55g$ of $C_2H_3Cl_3O_2$

The mass of chloral hydrate will be, 1.55 g

(f) To calculate the mass of exactly 500 molecules of chloral hydrate.

As, $6.022\times 10^{23}$ molecules of chloral hydrate has 165.5 g mass of chloral hydrate

So, 500 molecules of chloral hydrate has $\frac{6.022\times 10^{23}}{500}\times 165.5=1.99\times 10^{23}$ mass of chloral hydrate

The mass of exactly 500 molecules of chloral hydrate is, $1.99\times 10^{23}$

3 0

3 years ago

What is a mixture of two insoluble mixtures called

madreJ [45]

Answer:

Emulsion

Explanation:

Emulsion is a special type of mixture formed by combining two liquids that do not normally mix. An example of emulsion is;

Oil and Water

5 0

3 years ago