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3 years ago

In a chemical reaction, __________ are the substances present after the reaction.

Chemistry

2 answers:

chubhunter [2.5K]3 years ago

4 0

Answer:

products

Explanation:

Elenna [48]3 years ago

3 0

Explanation: Substances present BEFORE a reaction occurs are described as reactants. Substances present AFTER a reaction has occurred are described as products.

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An analytical chemist weighs out 0.281g of an unknown diprotic acid into a 250mL volumetric flask and dilutes to the mark with d

Helen [10]

Answer:

166 g/mol

Explanation:

Step 1: Write the neutralization reaction

H₂A + 2 NaOH ⇒ Na₂A + 2 H₂O

Step 2: Calculate the reacting moles of NaOH

48.3 mL of 0.0700 M NaOH react.

0.0483 L × 0.0700 mol/L = 3.38 × 10⁻³ mol

Step 3: Calculate the reacting moles of H₂A

The molar ratio of H₂A to NaOH is 1:2. The reacting moles of H₂A are 1/2 × 3.38 × 10⁻³ mol = 1.69 × 10⁻³ mol.

Step 4: Calculate the molar mass of H₂A

1.69 × 10⁻³ moles of H₂A have a mass of 0.281 g. The molar mass of H₂A is:

M = 0.281 g / 1.69 × 10⁻³ mol = 166 g/mol

6 0

3 years ago

Calcium ions that act as second messengers are stored in _____.

bagirrra123 [75]

Answer:

Endoplasmic reticulum.

Explanation:

Second messengers are known as intracellular signaling molecules released from the cell in response to exposure to extracellular signaling molecules. Second messenger activate physiological changes at a cellular level, for example proliferation, migration, differentiation, survival, and apoptosis.

Calcium ions are hydrophilic, water-soluble molecules. They are present in intracellular component know as endoplasmic reticulum and quickly released when needed. They are necessary for many important functions including fertilization, muscle contractions, and neurotransmitter release.

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3 years ago

Why could element 119 be right below Fr in the periodic table if discovered?

faust18 [17]

Answer:

Ununennium, also known as eka-francium or element 119, is the hypothetical chemical element with symbol Uue and atomic number 119. Ununennium and Uue are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkali metal, and the first element in the eighth period. It is the lightest element that has not yet been synthesized.

Explanation:

7 0

3 years ago

Consider the decomposition of red mercury(II) oxide under standard state conditions. )H0 T SFE ڮ( H M 0 H (a) Is the decompositi

sertanlavr [38]

The question is incomplete, complete question is :

Consider the decomposition of red mercury(II) oxide under standard state conditions.

$2HgO(s)\rightarrow 2Hg(l)+O_2(g)$

Given :

$\Delta S_{HgO}^o=70.29 J/mol K$

$\Delta S_{Hg}^o=75.9 J/mol K$

$\Delta S_{O_2}^o=205.2 J/mol K$

Enthalpy change of the reaction = ΔH = -90.83 kJ/mol

(a) Is the decomposition spontaneous under standard state conditions?

(b) Above what temperature does the reaction become spontaneous?

Answer:

a) The decomposition is spontaneous under standard state conditions.

b)The reaction will spontaneous above -419.69 Kelvins.

Explanation:

$2HgO(s)\rightarrow 2Hg(l)+O_2(g)$

Given :

$\Delta S_{HgO}^o=70.29 J/mol K$

$\Delta S_{Hg}^o=75.9 J/mol K$

$\Delta S_{O_2}^o=205.2 J/mol K$

Entropy change of the reaction ; ΔS

$\Delta S=[2\times \Delta S_{Hg}^o+1\times \Delta S_{O_2}^o]-[2\times \Delta S_{HgO}^o]$

$=[2\times 75.9 J/mol K+1\times 205.2 J/molK]-[2\times 70.29 J/molK]=216.42 J/mol K$

Enthalpy change of the reaction = ΔH = -90.83 kJ/mol = -90830 J/mol K

1 kJ = 1000 J

At standard condition the value of temperature = T = 298 K

ΔG = ΔH - TΔS

ΔG = -90830 J/mol K - 298 K × 216.42 J/mol K = -155,323.16 J/mol

ΔG < 0 ( spontaneous)

The decomposition is spontaneous under standard state conditions.

b) Above what temperature does the reaction become spontaneous

Let the ΔG = 0

Enthalpy change of the reaction = ΔH = -90.83 kJ/mol = -90830 J/mol K

ΔG = ΔH - TΔS

0 = -90830 J/mol K - T × 216.42 J/mol K

T = -419.69 K

The reaction will spontaneous above -419.69 Kelvins.

6 0

3 years ago

isabel a scale on her clarinet as she plays from low notes to high notes, what happens to the sound wave the clarinet creates?

MA_775_DIABLO [31]

As the tone gets higher, the sound waves get closer together

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3 years ago