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3 years ago

Calculate the percent errorin a length measurementof 4.45cm if the correct value is 4.06

Chemistry

1 answer:

FinnZ [79.3K]3 years ago

3 0

Answer:

9.6 %

Explanation:

Step 1: How to define percent error ?

⇒ % error is the difference between a measured value and the known or accepted value

⇒Percent error is calculated using the following formula:

⇒%error = | Experimental value-theoretical value/theoretical value | x100%

⇔ this can be written as well as : error = (| Experimental value/ theoretical value | - | Theoretical value / Theoretical value | ) x100%

Step 2: Calculate % error

In this case, this means :

%error = ( |(4.45 cm - 4.06cm ) / 4.06cm | ) x100%

%error = 0.096 x100%

%error =9.6 %

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What is the process used to convert between moles, mass, volume, and particles?

Roman55 [17]

conversion between mass and moles#

 

A substance's molar mass is calculated by multiplying its relative atomic mass by the molar mass constant (1 g/mol). The molar mass constant can be used to convert mass to moles. By multiplying a given mass by the molar mass, the amount of moles of the substance can be calculated.

 

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2 years ago

"How much NH4Cl, when present in 2.00 liters of 0.200 M ammonia, will give a solution with pH = 8.20? For NH3, Kb = 1.8 x 10-5"

Andru [333]

Answer:

245.66g of NH₄Cl is the mass we need to add to obtain the desire pH

Explanation:

The mixture of NH3/NH4Cl produce a buffer. We can find the pH of a buffer using H-H equation:

pH = pKa + log [A⁻] / [HA]

Where [A⁻] is the molar concentration of the base, NH₃, and [HA] molar concentration of the acid, NH₄⁺. This molar concentration can be taken as the moles of each chemical

First, we need to find pKa of NH₃ using Kb. Then, the moles of NH₃ and finally replace these values in H-H equation to solve moles of NH₄Cl we need to obtain the desire pH.

pKa NH₃/NH₄⁺

pKb = - log Kb

pKb = -log 1.8x10⁻⁵ = 4.74

pKa = 14 - pKb

pKa = 14 - 4.74

pKa = 9.26

Moles NH₃

2.00L ₓ (0.200mol NH₃ / L) = 0.400 moles NH₃

H-H equation:

pH = pKa + log [NH₃] / [NH₄Cl]

8.20 = 9.26 + log [0.400 moles] / [NH₄Cl]

-1.06 = log [0.400 moles] / [NH₄Cl]

0.0087 = [0.400 moles] / [NH₄Cl]

[NH₄Cl] = 0.400 moles / 0.0087

[NH₄Cl] = 4.59 moles of NH₄Cl we need to add to original solution to obtain a pH of 8.20. In grams (Using molar mass NH₄Cl=53.491g/mol):

4.59 moles NH₄Cl ₓ (53.491g / mol) =

<h3>245.66g of NH₄Cl is the mass we need to add to obtain the desire pH</h3>

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3 years ago

What is chemical reaction?

Aliun [14]

Answer:

a process that involves rearrangement of the molecular or ionic structure of a substance, as distinct from a change in physical form or a nuclear reaction

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2 years ago

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The following choices contain densities of various materials. Based on these data, which will yield the fastest seismic velocity

Eduardwww [97]

Answer:

D. 5.6 g/cm^3

Explanation:

On the average seismic velocity increases with increase in depth due higher the pressure and more compaction

sand and shales in the Niger Delta Basin density–velocity relationship is

P = 0.31×V^0.25

A derivation of the original Gardner equation to calculate the average densities for sands and shales in wells.

ρ = α ×V^β

where

ρ = bulk density in g/cm3,

V = P-wave velocity,

α = 0.31 for V (m/s) and 0.23 for V(ft/s) and

β = 0.25.

Such that

ρ = 0.31 ×V^0.25

So the fastest seismic velocity will be in the densest material which is D. 5.6 g/cm3

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3 years ago

How many liters of oxygen are in 8.32 moles of oxygen at STP

Jlenok [28]

Answer:

186 Liters at STP conditions

Explanation:

1 mole of any gas at STP conditions occupies 22.4 Liters.

Therefore, 8.32 moles O₂(g) = 8.32 moles x 22.4Liters/mole = 186 Liters (3 sig.figs.)

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2 years ago