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3 years ago

Can you help me on this since im struggling on this since day 1

Chemistry

1 answer:

emmasim [6.3K]3 years ago

3 0

Of Ok here is what I am thinking.

Simple replacement means when one element or compound moves out of another element and is replaced by this compound.

For example if you have A+BC ----- AC + B

Most of the time the one which is replaced is found on the right and the left one is going be only one element or compound.

Double replacement means when the two compounds exchange the positive and negative ions. Ok let see this example:

AB+ CD------- AD+ BC
this means if A have + sign and D has - sign they will share to form new compound the same is true for DC. Don't forget that all compounds are formed from positive and negative ions.

QUESTIONS
CUSO4 + NA2S---- CUS + Naso4[ double replacement]
KBR +Pb[CLO3]2------K[clo3]2 +PbBr [ double replacement]
I do not think these questions can be single replacement.
I hope this may helps you.

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Consider these elements: p, ca, si, s, ga. a. write the electron configuration for each element

dimulka [17.4K]

Method:

1) Find the atomic number in a periodic table: the number of electrons equal the atomic number

2) Use Aufbau rule

Element atomic number electron configuration

P 15 1s2 2s2 2p6 3s2 3p3

Ca 20 1s2 2s2 2p6 3s2 3p6 4s2

Si 14 1s2 2s2 2p6 3s2 3p2

S 16 1s2 2s2 2p6 3s2 3p4

Ga 31. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p

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4 years ago

Which of these describes an exothermic reaction?

Paul [167]

A nswer: -

C. Energy is released by the reaction

Explanation:-

An exothermic reaction is one in which during the progress of the reaction heat is evolved.

So energy is released by the reaction.

It cannot be created as energy is neither created nor destroyed as per the Law of conservation of energy. Energy is not transferred either.

The energy released during the progress of the reaction originates from the chemical bonds of the reactants as they break during their conversion into products.

3 0

3 years ago

Read 2 more answers

Dinitrogen tetraoxide, N2O4, decomposes to nitrogen dioxide, NO2, in a first-order process. If k = 1.5 x 103 s-1 at 5 ºC and k =

Arada [10]

Answer:

The activation energy for the decomposition = 33813.28 J/mol

Explanation:

Using the expression,

$\ln \dfrac{k_{1}}{k_{2}} =-\dfrac{E_{a}}{R} \left (\dfrac{1}{T_1}-\dfrac{1}{T_2} \right )$

Wherem

$k_1\ is\ the\ rate\ constant\ at\ T_1$

$k_2\ is\ the\ rate\ constant\ at\ T_2$

$E_a$ is the activation energy

R is Gas constant having value = 8.314 J / K mol

Thus, given that, $E_a$ = ?

$k_2=4.0\times 10^3s^{-1}$

$k_1=1.5\times 10^3s^{-1}$

$T_1=5\ ^0C$

$T_2=25\ ^0C$

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T = (5 + 273.15) K = 278.15 K

T = (25 + 273.15) K = 298.15 K

$T_1=278.15\ K$

$T_2=298.15\ K$

So,

$\ln \frac{1.5\times 10^3}{4.0\times 10^3}\:=-\frac{E_{a}}{8.314}\times \left(\frac{1}{278.15}-\frac{1}{298.15}\right)$

$E_a=-\ln \frac{1.5\times \:10^3}{4.0\times \:10^3}\:\times \frac{8.314}{\left(\frac{1}{278.15}-\frac{1}{298.15}\right)}$

$E_a=-\frac{8.314\ln \left(\frac{1.5\times \:10^3}{4\times \:10^3}\right)}{\frac{1}{278.15}-\frac{1}{298.15}}$

$E_a=-\frac{689483.53266 \ln \left(\frac{1.5}{4}\right)}{20}$

$E_a=33813.28\ J/mol$

The activation energy for the decomposition = 33813.28 J/mol

8 0

3 years ago

It asks for the percentage but I’m not sure how to find it when the answer is 67.1%

Vlada [557]

Since a percentage is out of 100, do the % / 100

Divide the percent by 100

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3 years ago

How are photons emitted by atoms?

Paul [167]

Explanation:

When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.

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3 years ago

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