The rainforest contains what percentage of all of the species in the world?

Why do you think it is important to use the same blanace throughout the entire experiment?

Zepler [3.9K]

It is important to use the same balance throughout the entire experiment since the calibration of each balance is not the same and changing balances could result in a systematic error.

There are three types of errors that could affect the results of the experiment. The effect of random or indeterminate errors is hard to predict, its effect on the results of the experiment could be different every time. The second type of error is the systematic or determinate error, which causes a shift in results in a specific direction. The last type of error in an experiment is human error.

The type of error that could be related to the use of different balances throughout the experiment is the systematic error. Instruments could be a source of error especially if they are poorly calibrated. Also, analytical balances are calibrated differently which may result in inaccuracy in the weighing of chemicals.

To learn more, please refer to brainly.com/question/11541675.

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6 0

2 years ago

Entropy is greater at higher trophic levels than at lower levels.. True of False

loris [4]

Answer: True

It is true that entropy is greater at higher trophic levels compared to the lower levels. The amount of energy and entropy in a certain food chain varies between trophic level. It specifically increases from one trophic level to another.

8 0

3 years ago

Read 2 more answers

Can somebody help me with this also plz

just olya [345]

ANSWER:

4 a) Specific elements have more than one oxidation state, demonstrating variable valency.

For example, the following transition metals demonstrate varied valence states: $Fe^{2+}$ , $Fe^{3+}$ , $Cr^{2+}, Cr^{3+}$ , etc.

Normal metals such as $Pb^{2+} and Pb^{4+}$ also show variable valencies. Certain non-metals are also found to show more than one valence state $Pb^{3+} and Pb^{5+}.$

4 b) Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons.

For example, Carbon-14 is a naturally occurring radioactive isotope of carbon, having six protons and eight neutrons in the nucleus. However, C-14 does not last forever and there will come a time when it loses its extra neutrons and becomes Carbon-12.

5 a) $2Fe + 3Cl_2$ → $2FeCl_3$

5 b) $3Pb + 8HNO_3$ → $3Pb (NO_3)_2 + 4H_2O + 2NO_2$

5 c) $Zn + H_2SO_4$ → $ZnSO_4 + H_2$ (already balanced so don't need to change)

5 d) $2H_2 + O_2$ → $2H_2O$

5 e) $2Mg + 2HCl$ → $2MgCl + H_2$

EXPLANATION (IF NEEDED):

1. Write out how many atoms of each element is on the left (reactant side) and right (product side) of the arrow.

2. Start multiplying each side accordingly to try to get atoms of the elements on both sides equal.

EXAMPLE OF BALANCING:

8 0

3 years ago

. What mass of ammonium chloride must be added to 250. mL of water to give a solution with pH

Eduardwww [97]

The mass of ammonium chloride that must be added is : ( A ) 4.7 g

<u>Given data :</u>

Volume of water ( V ) = 250 mL = 0.25 L

pH of solution = 4.85

Kb = 1.8 * 10⁻⁵

Kw = 10⁻¹⁴

Given that the dissolution of NH₄Cl gives NH₄⁺⁺ and Cl⁻ ions the equation is written as :

NH₄CI + H₂O ⇄ NH₃ + H₃O⁺

where conc of H₃O⁺

[ H₃O⁺ ] = $\sqrt{Ka.C}$ and Ka = Kw / Kb

∴ Ka = 5.56 * 10⁻¹⁰

Next step : Determine the concentration of H₃O⁺ in the solution

pH = - log [ H₃O⁺ ] = 4.85

∴ [ H₃O⁺ ] in the solution = 1.14125 * 10⁻⁵

Next step : Determine the concentration of NH₄CI in the solution

C = [ H₃O⁺ ]² / Ka

= ( 1.14125 * 10⁻⁵ )² / 5.56 * 10⁻¹⁰

= 0.359 mol / L

Determine the number of moles of NH₄CI in the solution

n = C . V

= 0.359 mol / L * 0.25 L = 0.08979 mole

Final step : determine the mass of ammonium chloride that must be added to 250 mL

mass = n * molar mass

= 0.08979 * 53.5 g/mol

= 4.80 g ≈ 4.7 grams

Therefore we can conclude that the mass of ammonium chloride that must be added is 4.7 g

Learn more about ammonium chloride : brainly.com/question/13050932

8 0

2 years ago

what is the mass of water vapor produced when 3.2 liters reacts with 8.7 liters of oxygen gas at STP?

uranmaximum [27]

Answer:

2.57g

Explanation:

First, let us write a balanced equation for the reaction. This is illustrated below:

2H2 + O2 —> 2H2O

Next let us determine the limiting reactant. This is achieved as follows:

From the equation,

2L H2 required 1L of O2.

Therefore, 3.2L of H will require = 3.2/2 = 1.6L of O2

From the calculation above, O2 is excess because the volume of O2 given from the question is far greater than the volume of O2 obtained from our calculation. Therefore, H2 is the limiting reactant.

Now let us covert 3.2L of H2 to mole. This is illustrated below:

1mole of a gas occupy 22.4L at stp

Therefore, Xmol of H2 will occupy 3.2L i.e

Xmol of H2 = 3.2/22.4 = 0.143mol

From the equation,

2moles of H2 produced 2moles of H2O.

Therefore, 0.143mol of H2 will also produce 0.143moles of H2O.

Now, we can obtain the mass of the water vapour produced by convert 0.143mol of H2O to gram. This is illustrated below:

Molar Mass of H2O = (2x1) + 16 = 2 + 16 = 18g/mol

Number of mole of H2O = 0.143mol

Mass of H2O =?

Mass = mole x Molar Mass

Mass of H2O = 0.143 x 18 = 2.57g

The mass of water vapour produce is 2.57g

8 0

3 years ago