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2 years ago

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What information does the atomic number of an element provide?. A. the number of protons in one atom of the element. . B. the nu

mber of electrons in one atom of the element. . C.the number of neutrons in one atom of the element. . D. the total number of protons and neutrons in one atom of the element

2 answers:

Galina-37 [17]2 years ago

6 0

The correct answer for the given question above would be option A. The information that the atomic number of an element provides is the number of protons in one atom of the element. This also provides the chemical properties of an element as well as the total positive charges.

shepuryov [24]2 years ago

5 0

D. the total number of protons and neutrons in a atom of the element.

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(LO 37,45) A reaction is 75% complete in 45.0 min. How long after its start will the reaction be 50% complete if it is (A) first

seropon [69]

Answer:

A) t = 22.5 min and B) t = 29.94 min

Explanation:

Initial concentration, [A]₀ = 100

Final concentration = 100 -75 = 25

Time = 45 min

A) First order reaction

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[25] − ln[100] = - 45k

-1.386 = -45k

k = 0.0308 min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[50] − ln[100] = - 0.0308 * t

-0.693 = -0.0308 * t

t = 22.5 min

B) Zero Order

[A] = [A]₀ − kt

Using the values from the initial reaction and solving for k, we have;

25 = 100 - k(45)

-75 = -45k

k = 1.67 M min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

[A] = [A]₀ − kt

50 = 100 - (1.67)t

-50 = - 1.67t

t = 29.94 min

3 0

3 years ago

In ionic bonds, valence electrons are

Serjik [45]

Answer:

Valence Electrons are transferred/exchanged

6 0

2 years ago

Complete and balance the chemical equations for the precipitation reactions, if any, between the following pairs of reactants, a

Crank

Explanation:

a. $Pb(NO_3)_2(aq) + Na_2SO_4(aq)$ → ?

$Pb(NO_3)_2(aq) + Na_2SO_4(aq)\rightarrow PbSO_4(s)+2NaNO_3(aq)$

$Pb(NO_3)_2(aq)\rightarrow Pb^{2+}(aq)+2NO_3^{-}(aq)$

$Na_2SO_4(aq)\rightarrow 2Na^++SO_4^{2-}(aq)$

$Pb^{2+}(aq)+2NO_3^{-}(aq)+2Na^++SO_4^{2-}(aq)\rightarrow PbSO_4(s)+2Na^++2NO_3^{-}(aq)$

Removing common ions from both sides, we get the net ionic equation:

$Pb^{2+}(aq)+SO_4^{2-}(aq)\rightarrow PbSO_4(s)$

b. $NiCl_2(aq) + NH_4NO_3(aq)$ →

$NiCl_2(aq) + NH4NO_3(aq) \rightarrow Ni(NO_3)_2+NH_4Cl(aq)$

No precipitation is occuring.

c. $Fe_Cl2(aq) + Na_2S(aq)$ →

$FeCl_2(aq) + Na_2S(aq)\rightarrow FeS(s)+2NaCl(aq)$

$FeCl_2(aq)\rightarrow Fe^{2+}(aq)+2Cl^{-}(aq)$

$Na_2S(aq)\rightarrow 2Na^++S{2-}(aq)$

$Fe^{2+}(aq)+2Cl^{-}(aq)+2Na^++S^{2-}(aq)\rightarrow FeS(s)+2Na^++2Cl^{-}(aq)$

Removing common ions from both sides, we get the net ionic equation:

$Fe^{2+}(aq)+S^{2-}(aq)\rightarrow FeS(s)$

d. $MgSO_4(aq) + BaCl_2(aq)$ →

$MgSO4(aq) + BaCl2(aq)\rightarrow BaSO_4(s)+MgCl_2$

$MgSO_4(aq)\rightarrow Mg^{2+}(aq)+SO_4^{2-}(aq)$

$BaCl_2(aq)\rightarrow Ba^{2+}+2Cl^{-}(aq)$

$Mg^{2+}(aq)+SO_4^{2-}(aq)+Ba^{2+}+2Cl^{-}(aq)(aq)\rightarrow BaSO_4(s)+Mg^{2+}(aq)+2Cl^{-}(aq)$

Removing common ions from both sides, we get the net ionic equation:

$Ba^{2+}(aq)+SO_4^{2-}(aq)\rightarrow BaSO_4(s)$

5 0

3 years ago

Research three different types of fire extinguisher and explain how these can be used to put out different fires, you must relat

Vilka [71]

The fire triangle is composed of
1) heat
2) fuel
3) oxidizing agent (oxygen)

Types of fire extinguishers:
1) Water and Foam - <span> extinguish the fire by taking away the </span>heat<span> element of the fire triangle. Foam agents separate the </span>oxygen<span> element from the other elements.</span>
2) Carbon dioxide - <span>extinguish fire by taking away the </span>oxygen<span> element of the fire triangle and also be removing the </span>heat<span> with a very cold discharge.</span>
3) Dry Chemical - <span>extinguish the fire primarily by interrupting the </span>chemical reaction<span> of the fire triangle.</span>
4) Wet Chemical - <span>extinguishes the fire by removing the heat of the fire triangle and prevents re-ignition by creating a barrier between the </span>oxygen<span> and </span>fuel<span> elements</span>
5) Clean Agent - <span>extinguish the fire by interrupting the </span>chemical reaction<span> of the fire triangle</span>
6) Dry Powder - extinguish the fire by separating thefuel<span> from the </span>oxygen<span> element or by removing the </span>heat<span> element of the fire triangle</span>
7) Water Mist - <span>extinguish the fire by taking away the </span>heatelement of the fire triangle
8) Cartridge Operated Dry Chemical - extinguish the fire primarily by interrupting the chemical reaction<span> of the fire triangle</span>

7 0

3 years ago

12.47 g of ammonium nitrate are dissolved in water, then diluted to 250 ml. What is the molarity of the resulting solution?

slega [8]

<h3><u>Answer;</u></h3>

= 0.6224 M

<h3><u>Explanation</u>;</h3>

Molarity is given by the formula;

Molarity = Number of moles/Volume

But moles = mass/Molar mass

Thus;

Moles = 12.47 g/80.043 g/mol

= 0.1556 Moles

Therefore;

Molarity = 0.1556 moles/0.25

<h3> <u>= 0.6224 M</u></h3>

6 0

3 years ago