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Scorpion4ik [409]
3 years ago
11

QUESTION 1

Chemistry
2 answers:
zhenek [66]3 years ago
6 0
1. Triassic
2. eon > era > period
3. The scientists study fossils and rock layers to find major changes.
otez555 [7]3 years ago
3 0
1. Terrassic:  <span>Relating to or denoting the earliest period of the Mesozoic era, between the Permian and Jurassic periods.
2. E</span>on > Era > Period:  An Eon is a large amount of time, An Era is <span>a long and distinct period of history, A length of time.
3. Scientists define the segments of the geological time scale by studying fossil and rock layers for major changes.</span>
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Important substances found in food, which promote growth and good health
Rzqust [24]
Protein would be the main one.
6 0
3 years ago
Read 2 more answers
A dosage is prescribed as 4.00 mg of medicine per kg of body weight.What dose should be given to a 112 pound person
vodka [1.7K]

Answer:

203.64 mg

Explanation:

112/2.2= 50.91

50.91x4.00= 203.64

4 0
3 years ago
Why is it better to use deionized water in chemistry experiments
Leno4ka [110]

Answer:

Laboratories use both distilled water and deionized water as controls in experiments. Deionization removes only non-charged organic matter from the water.

Explanation:

Distilled water removes even more impurities than deionization does, if the water undergoes a filtering process before boiling and distillation.

6 0
3 years ago
A 3.4 g sample of an unknown monoprotic organic acid composed of C,H, and O is burned in air to produce 8.58 grams of carbon dio
Pavlova-9 [17]

Answer:

C_7H_6O_2

Explanation:

Hello there!

In this case, we can divide the problem in three stages: (1) determine the empirical formula with the combustion analysis, (2) compute the molar mass of acid via the moles of the acid in the neutralization and (3) determine the molecular formula.

(1) In this case, since 8.58 g of carbon dioxide are released, we can first compute the moles of carbon in the compound:

n_C=8.58gCO_2*\frac{1molCO_2}{44.01gCO_2}*\frac{1molC}{1molCO_2}=0.195molC

And the moles of hydrogen due to the produced 1.50 grams of water:

n_H=1.50gH_2O*\frac{1molH_2O}{18.02gH_2O}*\frac{2molH}{1molH_2O}  =0.166molH

Next, to compute the mass and moles of oxygen, we need to use the initial 3.4 g of the acid:

m_O=3.4g-0.195molC*\frac{12.01gC}{1molC}-0.166molH*\frac{1.01gH}{1molH} =0.89gO\\\\n_O=0.89gO*\frac{1molO}{16.0gO}=0.0556molO

Thus, the subscripts in the empirical formula are:

C=\frac{0.195}{0.0556}=3.5 \\\\H=\frac{0.166}{0.0556}=3\\\\O=\frac{0.0556}{0.0556}=1\\\\C_7H_6O_2

As they cannot be fractions.

(2) In this case, since the acid is monoprotic, we can compute the moles by multiplying the concentration and volume of KOH:

n_{KOH}=0.279L*0.1mol/L\\\\n_{KOH}=0.0279mol

Which are equal to the moles of the acid:

n_{acid}=0.0279mol

And the molar mass:

MM_{acid}=\frac{3.4g}{0.0279mol} =121.86g/mol

(3) Finally, since the molar mass of the empirical formula is:

7*12.01 + 6*1.01 + 2*16.00 = 122.13 g/mol

Thus, since the ratio of molar masses is 122.86/122.13 = 1, we infer that the empirical formula equals the molecular one:

C_7H_6O_2

Best regards!

8 0
3 years ago
The K w for water at 0 ∘ C is 0.12 × 10 − 14 M 2 . Calculate the pH of a neutral aqueous solution at 0 ∘ C . p H = Is a pH = 7.2
Karo-lina-s [1.5K]

Answer:

pH → 7.46

Explanation:

We begin with the autoionization of water. This equilibrium reaction is:

2H₂O  ⇄   H₃O⁺  +  OH⁻            Kw = 1×10⁻¹⁴         at 25°C

Kw = [H₃O⁺] . [OH⁻]

We do not consider [H₂O] in the expression for the constant.

[H₃O⁺] = [OH⁻] = √1×10⁻¹⁴   →  1×10⁻⁷ M

Kw depends on the temperature

0.12×10⁻¹⁴ = [H₃O⁺] . [OH⁻]  → [H₃O⁺] = [OH⁻]         at 0°C

√0.12×10⁻¹⁴ = [H₃O⁺] → 3.46×10⁻⁸ M

- log [H₃O⁺] = pH

pH = - log 3.46×10⁻⁸ → 7.46

8 0
3 years ago
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