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3 years ago

Which example illustrates a chemical change

Chemistry

2 answers:

Svetllana [295]3 years ago

7 0

Burning wood because heat indicates a chemical change

Anastasy [175]3 years ago

3 0

Burning wood since it is changing into a new substance, whereas the other examples are not

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Of the following choices, pick all that are uses for radiation. Check all that

Novosadov [1.4K]

A B C these are the answers hopes this help <3

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2 years ago

Tips for memorizing the first 20 elements of the periodic table?

Anna [14]

Answer:

hydrant flying with balloon, balloon has lithp letting air out, bee: really yum balloon

= = = =

hydrogen helium lithium beryllium

be bore on the balloon, balloon pops, hydrant drops and makes a car bomb

= =

boron carbon

night row general gets hurt by car bomb nearby, that general gets off boat

nitrogen

wearing oxygen mask, mask is full of fluride gel, then he got neon teeth

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oxygen fluorine neon

(try making a story out of the elements, use your imagenation)

7 0

2 years ago

Read 2 more answers

In an ion with an unknown charge, the total mass of all the electrons was determined to be 2.19 ✕ 10−26 g, while the total mass

Ilya [14]

Answer:

$\large \boxed{\text{Fe$^{{2+}}$}}$

Explanation:

1. Number of electrons

$\text{Number of electrons} = 2.19 \times 10^{-26}\text{ g} \times \dfrac{\text{1 electron}}{9.109 \times 10^{-28}\text{ g}} = \text{24 electrons}$

2. Number of protons

$\text{Number of protons} = 4.34 \times 10^{-23}\text{ g} \times \dfrac{\text{1 proton}}{1.673 \times 10^{-24}\text{ g}} = \text{26 protons}$

3. Identify the ion

An atom with 26 protons is iron, Fe.

A neutral atom of iron would have 26 electrons.

The ion has only 24 electrons, so it has lost two. The ion must have a charge of +2.

$\text{The symbol for the ion is $\large \boxed{\textbf{Fe$^{\mathbf{2+}}$}}$}$

4 0

3 years ago

True or False? The following set of quantum numbers is acceptable (0, 0, 0, +1/2). Explain.

leonid [27]

Answer:

False

Explanation:

The values of the principal quantum number range from 1- infinity. This implies that there is no such thing as an energy level with n=0.

Hence this can not be an acceptable set of quantum numbers when n=0.

8 0

3 years ago

From the enthalpies of reaction H2(g)+F2(g)→2HF(g)ΔH=−537kJ C(s)+2F2(g)→CF4(g)ΔH=−680kJ 2C(s)+2H2(g)→C2H4(g)ΔH=+52.3kJ calculate

DIA [1.3K]

Answer:

$\Delta H$ for the given reaction is -2486.3 kJ

Explanation:

The given equation can be written as a combination of the following equation:

$2H_{2}(g)+2F_{2}(g)\rightarrow 4HF(g)$ ; $\Delta H_{1}= (2\times -537kJ)=-1074 kJ$

$2C(s)+4F_{2}(g)\rightarrow 2CF_{4}(g)$ ; $\Delta H_{2}=(2\times -680kJ)=-1360kJ$

$C_{2}H_{4}(g)\rightarrow 2C(s)+2H_{2}(g)$ ; $\Delta H_{3}=-52.3kJ$

-----------------------------------------------------------------------------------

$C_{2}H_{4}(g)+6F_{2}(g)\rightarrow 2CF_{4}(g)+4HF(g)$

$\Delta H=\Delta H_{1}+\Delta H_{2}+\Delta H_{3}=(-1074-1360-52.3)kJ=-2486.3kJ$

6 0

3 years ago