All categories

2 years ago

How have organisms changed over time, according to the fossil record?

Chemistry

1 answer:

Yuri [45]2 years ago

6 0

Answer:

As the world changes, plants and animals change with it. Aside from a few living fossils, the species we see today are very different from species that lived in the past. Thus, the fossil record can be used to show that organisms changed to meet new conditions. This is the result of evolution of species over time.

hope this helps

have a good day :)

Explanation:

You might be interested in

The expression of the theoretical yield (TY) in function of limiting reagent (LR) of a reaction is as follows: TY = ideal mole r

spin [16.1K]

Answer: The theoretical yield of acetanilide is 6.5 grams.

Explanation:

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

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For aniline:

Given mass of aniline = $4.50\times 10^0=4.50g$ (We know that: $10^0=1$ )

Molar mass of aniline = 93.13 g/mol

Putting values in equation 1, we get:

$\text{Moles of aniline}=\frac{4.50g}{93.13g/mol}=0.048mol$

For acetic anhydride:

To calculate the mass of acetic anhydride, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Volume of acetic anhydride = $(1.25\times \text{Mass of aniline})=1.25\times 4.50=5.625mL$

Density of acetic anhydride = 1.08 g/mL

Putting values in above equation:

$1.08g/mL=\frac{\text{Mass of acetic anhydride}}{5.625mL}\\\\\text{Mass of acetic anhydride}=(1.08g/mL\times 5.625mL)=6.08g$

Given mass of acetic anhydride = 6.08 g

Molar mass of acetic anhydride = 102.1 g/mol

Putting values in equation 1, we get:

$\text{Moles of acetic anhydride}=\frac{6.08g}{102.1g/mol}=0.06mol$

The chemical equation for the reaction of aniline and acetic anhydride follows:

$C_6H_5NH_2+CH_3COOCOCH_3\rightarrow C_6H_5NHCOCH_3+CH_3COOH$

By Stoichiometry of the reaction:

1 mole of aniline reacts with 1 mole of acetic anhydride

So, 0.048 moles of aniline will react with = $\frac{1}{1}\times 0.048=0.048mol$ of acetic anhydride

As, given amount of acetic anhydride is more than the required amount. So, it is considered as an excess reagent.

Thus, aniline is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of aniline produces 1 mole of acetanilide

So, 0.048 moles of aniline will produce = $\frac{1}{1}\times 0.048=0.048mol$ of acetanilide

Now, calculating the theoretical yield of acetanilide by using equation 1:

Moles of acetanilide = 0.048 moles

Molar mass of acetanilide = 135.17 g/mol

Putting values in equation 1, we get:

$0.048mol=\frac{\text{Mass of acetanilide}}{135.17g/mol}\\\\\text{Mass of acetanilide}=(0.048mol\times 135.17g/mol)=6.5g$

Hence, the theoretical yield of acetanilide is 6.5 grams.

3 0

3 years ago

The pH of a solution is 8. Some hydrochloric acid is added to the solution. Suggest the pH of the solution after mixing. pH=....

Molodets [167]

Answer:

Probably around 6 because the ph of hydrochloric acid is 3

Explanation:

3 0

2 years ago

What will determine the number of moles of hydronium in an aqueous solution of a strong monoprotic acid?.

marin [14]

Answer:

What will determine the number of moles of hydronium in an aqueous solution of a strong monoprotic acid? The amount of acid that was added.

Explanation:

3 0

2 years ago

Calculate the amount of HCN that gives the lethal dose in a small laboratory room measuring 12.0 ft×15.0 ft×8.60ft.

garik1379 [7]

Given:

Dimensions of the room= 12 ft * 15 ft * 8.60 ft

To determine:

The amount of HCN that gives the lethal dose in the room with the given dimensions

Explanation:

As per the World Health Organization, the lethal dose of HCN is around 300 ppm

300 ppm = 300 mg of HCN/ kg of inhaled air

Volume of air = volume of room = 12 * 15 *8.6 = 1548 ft³

Now, 1 ft³ = 28316.8 cm³

Therefore, the calculated volume of air corresponds to:

1548 * 28316.8 = 4.383 * 10⁷ cm3

Density of air (at room temperature 25 C) = 0.00118 g/cm3

Thus mass of air corresponding to the calculated volume is

Mass = Density * volume = 0.00118 g/cm3 * 4.383 * 10⁷ cm3

= 5.172*10⁴ g = 51.72 kg

Lethal amount of HCN corresponding to 51.72 kg of air would be.

= 51.72 kg air* 300 mg of HCN/1 kg air = 15516 mg

Ans: Lethal dose of HCN = 15.5 g

7 0

3 years ago

Q1.

valentinak56 [21]

Answer:

4.49dm3

Explanation:

2NH4Cl + Ca(OH)2 —> CaCl2 + 2NH3 + 2H2O

First, we need to convert 10g of ammonium chloride to mole. This is illustrated below:

Molar Mass of NH4Cl = 14 + (4x1) + 35.5 = 53.5g/mol

Mass of NH4Cl = 10g

Number of mole = Mass /Molar Mass

Number of mole of NH4Cl = 10/53.5 = 0.187mol

From the equation,

2moles of NH4Cl produced 2 moles of NH3.

Therefore, 0.187mol of NH4Cl will also produce 0.187mol of NH3

Now we can obtain the volume of NH3 produced by doing the following:

1mole of any gas occupy 24dm3

Therefore, 0.187mol of NH3 will occupy = 0.187 x 24 = 4.49dm3

4 0

3 years ago

How have organisms changed over time, according to the fossil record?​

How have organisms changed over time, according to the fossil record?