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3 years ago

9

Andrew walks through his garden and observes that the shapes of dewdrops are not always the same. Suppose he wants to investigat

e using the scientific method. Which questions are testable questions that he can ask to look into the reasons for the different shapes?

1 answer:

Allisa [31]3 years ago

6 0

Answer: A, C, E

Explanation: PLATO. all testable questions.

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Calculate the Standard Enthalpy of the reaction below:

Norma-Jean [14]

Answer:

(we use hess's law) it is so simple but the second reaction is not correct please right it

6 0

3 years ago

An amphoteric salt is one that contains an anion that can act as either an acid or a base in water. Baking soda, NaHCO3, is an e

LenKa [72]

Answer:

pH = 8.34

Explanation:

The equilbriums of the amphoteric HCO₃⁻ (Ion of NaHCO₃) are:

H₂CO₃ ⇄ <em>HCO₃⁻</em> + H⁺ Ka1 <em>-Here, HCO₃⁻ is acting as a base-</em>

<em>HCO₃⁻</em>⇄ CO₃²⁻ + H⁺ Ka2 <em>-Here, is acting as an acid-</em>

Where Ka1 = 4.3x10⁻⁷ and Ka2 = 4.8x10⁻¹¹. As pKa = -log Ka:

pKa1 = 6.37; pKa2 = 10.32

As the pH of amphoteric salts is:

pH = (pKa1 + pKa2) / 2

<h2>pH = 8.34</h2>

3 0

2 years ago

Classify each of the following equations as synthesis, decomposition, or replacement.

Sonja [21]

Answer: A. Is decomposition

B. Is synthesis where Na combines with Cl to form NaCl

C. Is single displacement or replacement. Mg displaces Cu.

Explanation:

7 0

3 years ago

Determine the formula weights of each of the following compounds.Part A) Nitrous oxide, N2O, known as laughing gas and used as a

densk [106]

Answer:

See explanation

Explanation:

a) Nitrous oxide (N2O) has a molar mass of 44.014 amu. It has 2 nitrogen atoms each with a mass of 14.007 amu and 1 oxygen atom with a mass of 16.0 amu.

Percentage nitrogen = (2*14.007 amu/ 44.014 amu ) *100% = 63.6%

Percentage oxygen = (16 amu/44.014 amu) * 100% = 36.4 %

63.6% + 36.4% = 100%

b) Benzoic acid (C7H6O2) has a molar mass of 122.13 amu. It has 6 hydrogen atoms each with a mass of 1.01 amu; it has 7 carbon atoms each with a mass of 12.01amu and 2 oxygen atoms with a mass of 16.0 amu.

Percentage hydrogen = (6*1.01 amu / 122.13 amu)*100% = 4.96%

Percentage carbon = (7*12.01 amu/ 122.13 amu)*100% = 68.8%

Percentage oxygen = (2*16 amu/ 122.13 amu) *100% = 26.2%

c) Magnesium hydroxide (Mg(OH)2) has a molecular mass of 58.32 amu. It has 2 hydrogen atoms each with a mass of 1.01 amu; it has 1 magnesium atom with a mass of 24.3 amu and two oxygen atoms with a mass of 16.0 amu.

Percentage hydrogen = (2*1.01 amu/ 58.32 amu) *100% = 3.46 %

Percentage magnesium = (24.3 amu/58.32 amu)*100% = 41.7%

Percentage oxygen = (2*16 amu/58.32 amu)*100% = 54.9%

d) Urea CO(NH2)2 has a molecular mass of 60.064 amu. It has 2 Nitrogen atoms each with a mass of 14.007 amu, 4 hydrogen atoms each with a mass of 1.01 amu,1 carbon atom with a mass of 12.01 amu and 1 oxygen atom with a mass of 16.0 amu.

Percentage nitrogen = (2*14.007 amu/ 60.064amu)*100% = 46.6%

Percentage hydrogen = (4*1.01 amu/60.064amu)*100% = 6.72%

Percentage carbon = (12.01 amu/60.064amu)*100% = 20.0%

Percentage oxygen = (16 amu/60.064amu)*100% = 26.6%

e) Osopentyl acetate (C7H14O2) has a molecular mass of 130.2 amu. It has 14 hydrogen atoms each with a mass of 1.01 amu,7 carbon atoms each with a mass of 12.01 amu and 2 oxygen atom with a mass of 16.0 amu.

Percentage hydrogen = (14*1.01 amu/130.2 amu)*100% = 10.8%

Percentage carbon = (7*12.01 amu/130.2 amu)*100% = 64.6%

Percentage oxygen =(2*16 amu/130.2 amu)*100% = 24.6%

7 0

3 years ago

If an element has an atomic number of 8 and an atomic mass number of 18, would it be an isotope? Why or why not?

hoa [83]

Answer:

It would be an isotope.

Background Information:

Isotopes are typically elements that have a different number of protons than neutrons. The atomic mass is the total number of protons and neutrons. The atomic number is the number of protons.

Explanation:

If the atomic number is the number of protons that means that this particular element has 8 protons. If the atomic mass is the total number of protons and neutrons then we can simply take away the amount of protons from that number, 18 - 8 = 10. If we take protons away from the number of protons and neutrons we are left with the number of neutrons. So there are 10 neutrons. Because there are 8 protons and 10 neutrons, or a different amount of neutrons and protons we know that this particular atom is an isotope.

3 0

3 years ago