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3 years ago

An exothermic reaction has a positive enthalpy (heat) of reaction.(T/F)

Chemistry

2 answers:

mestny [16]3 years ago

5 0

Answer:

True.

Explanation:

An exothermic reaction has a positive enthalpy (heat) of reaction. However, it can be negative in some circumstances.

Temka [501]3 years ago

4 0

Answer:

True.

Explanation:

True, An exothermic reaction has a positive enthalpy (heat) of reaction.

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If the compound contains 35.06 % cl by mass, what is the identity of the metal?

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Answer is: identity of the metal is gold (Au).

ω(Cl) = 35.06% ÷ 100%.

ω(Cl) = 0.3506; mass percentage of chlorine.

If we take 100 grams of the compound:

m(Cl) = ω(Cl) · m(compound).

ω(Cl) = 0.3506 · 100 g.

ω(Cl) = 35.06 g.

n(Cl) = m(Cl) ÷ M(Cl).

n(Cl) = 35.06 g ÷ 35.45 g/mol.

n(Cl) = 0.99 mol; amount of substance.

In molecule MCl₃: n(M) : n(Cl) = 1 : 3.

n(M) = 0.33 mol; amount of unknown metal.

M(M) = m(M) ÷ n(M).

M(M) = (100 g - 35.06 g) ÷ 0.33 mol.

M(M) = 196.8 g/mol; molar mass of the gold.

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Various properties of a liquid are recorded during an experiment. the volume of the liquid is measured to be 25.5 milliliters. t

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The liquid is blue is an example of qualitative data. Qualitative data is data that can not be represented by numbers. The volume and density are both quantitative data.

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Does NH3 dissolve in acetone?

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Acetone will react with ammonia. Acetone will act as an Lewis Acid and ammonia will act as a Lewis Base in this situation. The nitrogen in NH3 is very reactive because of its lone pair of electrons(The nitrogen is delta -ve), so it will attack the carbon cation center of the acetone (which is delta +ve).

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How did oxygen come up to make 21% of the earth's present atmosphere?

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A sample was prepared by mixing 18. ml of 3.00 x 10^-3 m crystal violet (cv) with 2.00 ml of 0.250 m naoh. calculate the resulti

Aleks [24]

Answer : The resulting concentrations of CV and NaOH are 0.0027 M and 0.025 M respectively.

Explanation :

Step 1 : Find moles of crystal violet and NaOH.

The molarity formula is

$Molarity = \frac{mol}{L}$

Molarity of crystal violet = $3.00 \times 10^{-3} = \frac{mol (CrystalViolet)}{L}$

The volume of crystal violet solution is 18 mL which is 0.018 L.

Moles of crystal violet = $3.00 \times 10^{-3} \times 0.018 = 5.4 \times 10^{-5}$

Moles of crystal violet = 5.4 x 10⁻⁵

Moles of NaOH = $Molarity \times L = 0.250 \times 0.00200 = 5.00 \times 10^{-4}$

Moles of NaOH = 5.00 x 10⁻⁴

Step 2 : Find total volume of the solution

The total volume of the solution after mixing NaOH and crystal violet is

0.018 L + 0.00200 = 0.020 L

Step 3 : Use molarity formula to find final concentrations

Molarity of crystal violet = $\frac{mol(CrystalViolet)}{Total Volume(L) } = \frac{5.4 \times 10^{-5}}{0.020} = 2.7 \times 10^{-3}$

Final concentration of CV = 0.0027 M

Molarity of NaOH= $\frac{mol(NaOH)}{Total Volume(L) } = \frac{5.00 \times 10^{-4}}{0.020} = 0.025 \times 10^{-3}$

NaOH is a strong base and dissociates completely as follows.

$NaOH (aq) \rightarrow Na^{+} (aq) + OH^{-} (aq)$

The mole ratio of NaOH and OH⁻ is 1:1 . Therefore the concentration of OH⁻ is same as that of NaOH.

Concentration of OH⁻ = 0.025 M

8 0

3 years ago