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3 years ago

Variable changed by the scientists what is being tested

Chemistry

2 answers:

Gnoma [55]3 years ago

6 0

Answer:

Hope this is helpful to you!

The independent variable is the one that is changed by the scientist. To insure a fair test, a good experiment has only ONE independent variable. As the scientist changes the independent variable, he or she records the data that they collect.

Dmitrij [34]3 years ago

6 0

Answer:

Explanation:

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How many atoms are in 2.10 g of K? molar mass of K=39.10g/mole.

Alborosie

Answer:

<h3>The answer is option B</h3>

Explanation:

To calculate the number of atoms we must first calculate the number of moles

Molar mass = mass / number of moles

number of moles = mass / Molar mass

Molar mass (K) = 39.10mole

mass = 2.10g

number of moles = 2.10/ 39.10

= 0.0537mol

After that we use the formula

N = n × L

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10^23 entities

Number of K atoms is

N = 0.0537 × 6.02 × 10^13

<h3>N = 3.23×10^22 atoms of K</h3>

Hope this helps you.

5 0

3 years ago

Are the particles in a solid in constant motion, or are they "frozen in place?"

Tems11 [23]

The molecules are frozen in place but still vibrate

3 0

3 years ago

Read 2 more answers

Calculate the volume of the acid solution and the volume of the conjugate base solution that would be needed to prepare a buffer

bogdanovich [222]

Answer:

Explanation:

This can be contradictory, depending on whether the 0.1 M

is the total species concentration or the concentration of each of the two components. I'll consider this to be the former...

VA− = 9.125 mL

VHA = 15.875 mL

The Henderson-Hasselbalch equation is:

pH = pKa + log [A−][HA]

We have a pH 4.5

solution of acetic acid and acetate, so from there we can get the ratio of weak acid to conjugate base:

[A−][HA]=10

pH − pKa = 104.5 − 4.74 = 0.5754

Now, if the total concentration is

0.10 M , then:

[HA] + [A−] 0.5754

[HA] = 0.10 M

⇒[HA] = 0.10 M 1.0000 +0.5754

= 0.0635 M

−−−−−−−−

⇒[A−] = 0.0365 M

−−−−−−−−

and these concentrations are AFTER mixing. Since the total volume is 50 mL , or 0.050 L, the mols of each component (which are constant!) are:

nA − = 0.0365 molL × 0.050L =

0.001825 mols

−−−−−−−−−−−−

nHA = 0.0635 molL × 0.050L =

0.003175 mols

−−−−−−−−−−−−

So, if both of the starting concentrations were

0.20 M, we can find the volume they each start with:

VA − = 1 L0.20mols

A− × 0.001825mols A− = 0.009125 L = 9.125 mL

−−−−−−−−

VHA = 1 L 0.20 mols HA × 0.003175

mols HA = 0.015875 L = 15.875 mL

−−−−−−−−−

And this should make sense, because the total starting volume is

25.000 mL , the total ending volume is twice as large; the total species concentration is half the concentration that both species started with.

6 0

3 years ago

Many esters have characteristic odors. Methyl salicylate exhibits a pleasant wintergreen odor. This ester can be prepared from s

hodyreva [135]

Answer:

Methanol would be used as a reagent in excess, since it is a very low-cost solvent. For product isolation, the first thing to do is remove the methanol through a distillation process. The residue produced can be dissolved in diethyl ether. Using a NaHCO₃ solution, extraction is performed. When it separates into two phases, the product will be in the ether and the reagent in the aqueous phase. The ether can also be removed by distillation, and at the end of this process you will have the product you want.

Explanation:

5 0

3 years ago

The equations given in the problem introduction can be added together to give the following reaction: overall: N2O4→2NO2 However

Murljashka [212]

Answer:

Reverse the $2 NO_2 \longrightarrow 2 NO + O_2$ reaction

Explanation:

Reactions:

$2 NO_2 \longrightarrow 2 NO + O_2$

$N_2O_4 \longrightarrow 2 NO + O_2$

Overall:

$N_2O_4 \longrightarrow 2 NO_2$

As can be seen, in the overall reaction we have $N_2O_4$ in the reactants like in the second reaction and $NO_2$ in the products. The $NO_2$ is in the first reaction but as a reactant so we need to reverse that reaction:

$2 NO + O_2 \longrightarrow 2 NO_2$

$N_2O_4 \longrightarrow 2 NO + O_2$

Combining:

$N_2O_4 + 2 NO + O_2\longrightarrow 2 NO + O_2 + 2 NO_2$

$N_2O_4 \longrightarrow 2 NO_2$

4 0

3 years ago