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Marysya12 [62]
3 years ago
14

What is litmus paper used for? To indicate if all the reactants have been used up to determine if a chemical reaction has occurr

ed to determine pH to detect the presence of water
Chemistry
1 answer:
rjkz [21]3 years ago
8 0
The main use of litmus is to test whether a solution is acidic or basic. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F).
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What is mb for CH3NH2….
drek231 [11]

Answer:

A.) K_b = \frac{[CH_3NH_3^+][OH^-]}{[CH_3NH_2]}

Explanation:

The general Kb expression is:

K_b = \frac{[HA][OH^-]}{[A^-]}

In this equation

-----> Kb = equilibrium constant

-----> [HA] = acid

-----> [A⁻] = base

Since liquids are not included in equilibrium expressions, H₂O should not be present. The products are in the numerator while the reactant are in the denominator. In this reaction, CH₃NH₂ is acting as a base and CH₃NH₃⁺ is acting as an acid.

As such, the expression is:

K_b = \frac{[CH_3NH_3^+][OH^-]}{[CH_3NH_2]}

7 0
2 years ago
How do the independent and dependent variables in an experiment compare?
DENIUS [597]
An independent variable<span> is the </span>variable<span> that is changed or controlled in a scientific </span>experiment<span> to test the effects on the </span>dependent variable<span>. </span>
4 0
3 years ago
Protein x has an absorptivity of 0.4 ml·mg-1 ·cm-1 at 280 nm. What is the absorbance at 280 nm of a 2.0 mg ·ml-1 solution of pro
Evgen [1.6K]

Absorbance measures the ability of the substance to absorb light at a specific wavelength.

Absorbance is also equal to the product of molar absorptivity, path length and molar concentration.

The mathematical expression is given as:

A= \epsilon l c       (1)

where, A = absorbance

\epsilon =  molar absorptivity

l = path length

c  = molar concentration.

The above formula is said to Beer's Law.

Absorptivity of protein x  = 0.4 mLmg^{-1}cm^{-1}

Path length = 1 cm

Molar concentration = 2.0 mg mL^{-1}

Put the values in formula (1)

Absorbance at 280 nm = 0.4 mL mg^{-1}cm^{-1}\times 1 cm \times 2.0 mg mL^{-1}

= 0.8

Thus, absorbance at 280 nm = 0.8

3 0
3 years ago
Aspirin (C9H8O4) may be synthesized by mixing salicylic acid (C7H6O3) with excess acetic anhydride (C4H6O3).
diamong [38]

Answer:

65.18% is the percent yield for this reaction.

Explanation:

C_7H_6O_3 + C_4H_6O_3\rightarrow C_9H_8O_4 + C_2H_4O_2

Moles of salicyclic acid = \frac{2.0 g}{138 g/mol}=0.01449 mol

According to reaction 1 mole of salicyclic acid gives 1 mole of aspirin .

Then 0.01449 mole of salicylic acid will give :

\frac{1}{1}\times 0.01449 mol=0.01449 mol of asprin

Mass of 0.01449 moles of aspirin :

= 0.01449 mol × 180 g/mol = 2.6082 g

Theoretical yield of aspirin = 2.6082 g

Experimental yield of aspirin = 1.7 g

The percent yield for this reaction:

\%(Yield)=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100

=\frac{1.7 g}{2.6082 g}\times 100=65.18\%

65.18% is the percent yield for this reaction.

5 0
3 years ago
What is the density of a mineral with a mass of 41.2 g and a volume 8.2 cm3?
dezoksy [38]
Hey there!:

mass = 41.2 g

Volume = 8.2 cm³

Therefore:

D = m / V

D = 41.2 / 8.2

D = 5.02 g/cm³
4 0
3 years ago
Read 2 more answers
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