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3 years ago

Which of these statements is false?

Chemistry

1 answer:

cluponka [151]3 years ago

6 0

Answer:

the nucleus of an atom is positivley charged

Explanation:

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An environmental scientist developed a new analytical method for the determination of cadmium (cd^2+) in mussels. To validate th

Anettt [7]

Answer:

The method is accurate in the calculation of the $Cu^+2$

Explanation:

As a first step we have to calculate the average concentration of $Cu^+2$ find it by the method.

$\frac{0.782+0.762+0.825+0.838+0.761 }{5} =0.79 ppm$

Then we have to find the standard deviation:

$s=\sqrt{\frac{1}{N-1}\sum_{i=1}^N(x_i-\bar{x})^2}=0.0359$

For the confidence interval we have to use the formula:

μ=Average± $\frac{t*s}{\sqrt{n} }$

Where:

t=t student constant with 95 % of confidence and 5 data=2.78

μ= $0.79$ ± $\frac{2.78*0.0359}{\sqrt{5} }$

upper limit: 0.84

lower limit: 0.75

If we compare the limits of the value obtanied by the method (Figure 1 Red line) with the reference material (Figure 1 blue line) we can see that the values obtained by the method are within the values suggested by the reference material. So, it's method is accurate.

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3 years ago

What is the amount of aluminum chloride produced from 40 moles of aluminum and excess chlorine?

Marrrta [24]

Answer:

is it 26.98

Explanation:

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2 years ago

Consider four elements from Group 7A: fluorine in the second period, chlorine in the third period, bromine in the fourth period,

madam [21]

Onization energy is the energy required to lose an electron and form an ion. The stronger is the attraction of the atom and the electron the higher the ionization energy, and the weaker is the attraction of the atom and the electron the higher the ionization energy. This leads to a clear trend in the periodic table. Given that the larger the atom the weaker the attraction of the atom to the valence electrons, the easier they will be released, and the lower the ionization energy. This is, as you go downward in a group, the ionization energy decreases. So, the element at the top of the group will exhibit the largest ionization energy. Therefore, the answer is that of the four elements of group 7A, fluorine will have the largest first ionization energy.

7 0

3 years ago

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A chemistry student needs to standardize a fresh solution of sodium hydroxide. She carefully weighs out 192.mg of oxalic acid H2

kap26 [50]

Answer:

The molarity of the NaOH solution is 0.076 M

Explanation:

Step 1: Data given

Mass of oxalic acid = 192 mg = 0.192 grams

volume = 250 mL = 0.250 L

Molar mass oxalic acid = 90.03 g/mol

Step 2: The balanced equation

H2C2O4 + 2NaOH → Na2C2O4 + H2O

Step 3: Calculate moles of oxalic acid

Moles oxalic acid = 0.192 grams / 90.03 g/mol

Moles oxalic acid = 0.00213 moles

Step 4: Calculate molarity of oxalic acid

Molarity = Moles / volume

Molarity = 0.00213 moles / 0.250 L

Molarity = 0.00852 M

Step 5: Calculate Molarity of NaOH

2 Ca*Va = Cb*Vb

with Ca = Molarity of oxalic acid = 0.00852 M

with Va = volume of oxalic acid = 0.250 L

with Cb = Molarity of NaOH = TO BE DETERMINED

with Vb = volume of 0.0558 L

Cb = (2*0.00852 * 0.25) / 0.0558

Cb = 0.076 M

The molarity of the NaOH solution is 0.076 M

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3 years ago

What is electron affinity? A. the energy change that happens when a neutral atom gains an electron B. the energy change that hap

lidiya [134]

Your answer is most likely:
A.

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3 years ago

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