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3 years ago

How do you find the mass number of an isotope?

Chemistry

1 answer:

solong [7]3 years ago

8 0

Answer:

The mass number of an isotope is the total number of protons and neutrons in an atomic nucleus. If you know that a nucleus has 6 protons and 6 neutrons, then its mass number is 12. If the nucleus has 6 protons and 7 neutrons, then its mass number is 13.

Explanation:

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If 45.0 mL of ethanol (density=0.789 g/mL) initially at 9.0 C is mixed with 45.0 mL of water (density=1.0 g/mL) initially at 28.

Klio2033 [76]

Answer : The final temperature of the mixture is $22.7^oC$

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

And as we know that,

Mass = Density × Volume

Thus, the formula becomes,

$(\rho_1\times V_1)\times c_1\times (T_f-T_1)=-(\rho_2\times V_2)\times c_2\times (T_f-T_2)$

where,

$c_1$ = specific heat of ethanol = $2.3J/g^oC$

$c_2$ = specific heat of water = $4.18J/g^oC$

$m_1$ = mass of ethanol

$m_2$ = mass of water

$\rho_1$ = density of ethanol = 0.789 g/mL

$\rho_2$ = density of water = 1.0 g/mL

$V_1$ = volume of ethanol = 45.0 mL

$V_2$ = volume of water = 45.0 mL

$T_f$ = final temperature of mixture = ?

$T_1$ = initial temperature of ethanol = $9.0^oC$

$T_2$ = initial temperature of water = $28.6^oC$

Now put all the given values in the above formula, we get

$(0.789g/mL\times 45.0mL)\times (2.3J/g^oC)\times (T_f-9.0)^oC=-(1.0g/mL\times 45.0mL)\times 4.18J/g^oC\times (T_f-28.6)^oC$

$T_f=22.7^oC$

Therefore, the final temperature of the mixture is $22.7^oC$

4 0

3 years ago

Writing the net ionic equation

vazorg [7]

First write the molecular equation with states:

(NH4)2S (aq) + 2AgNO3(aq) → Ag2S (s) + 2NH4NO3

Now write a full ionic equation by separating into ions all substances that dissociate: anything (s) (g) or (l) does not dissociate

2NH4 + (aq) + S 2-(aq) + 2Ag+ (aq) + 2NO3- (aq) → Ag2S(s) + 2NH4 + (aq) + 2NO3- (aq)

To write the NET IONIC equation, inspect the full ionic equation above and delete anything that appears on both sides of the → sign:

Net ionic equation:

S 2-(aq) + 2Ag + (aq) → Ag2S(s)

3 0

3 years ago

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Bohr's Model of the atom

AlexFokin [52]

Answer:

group 17 the halogen.as it has 7 electron in its outermost ring

3 0

2 years ago

What does volcanic ash add to the environment?

Travka [436]

Somethings that are beneficial is its good for plants, if it is very fine ash it is able to break down and quickly dissolve into the soil.

7 0

3 years ago

How many moles of nitrogen are contained in 18.65 L at STP?

stira [4]

1 mole of any gas under STP ----- 22.4 L

18.65 L*1 mol/22.4 L ≈ 0.8326 mol N2

8 0

3 years ago

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