All categories

3 years ago

The number of protons plus the number of neutrons equals the _____.

Chemistry

2 answers:

MrRa [10]3 years ago

7 0

It equals the atomic mass.

Zanzabum3 years ago

6 0

Answer: The number of protons plus the number of neutrons equals the atomic mass.

Explanation:

Atomic mass is defined as total number of protons and neutrons in the atom.

It is an average mass of an atom.

It is expressed in atomic mass unit that is a.m.u.

It is denoted with symbol 'A'.

$A =\text{number of protons + number of neutrons}$ .

You might be interested in

Elemental analysis of caffeine yields the following results: 49.49% C, 5.15% H, 28.87% N, and the remainder is O. What is the mo

vova2212 [387]

Answer:

The answer to your question is C₄H₅N₂O

Explanation:

Process

1.- Calculate the percent of oxygen in the sample

Percent of oxygen = 100 - 49.49 - 5.15 - 28.87

Percent of oxygen = 16.49 %

2.- Write the percents as grams

C = 49.49 g

H = 5.15 g

N = 28.87 g

O = 16.47 g

3.- Convert the grams to moles

C 12 g ------------------- 1 mol

49.49 g ---------------- x

x = (49.49 x 1) 12

x = 4.12 moles

H 1 g ------------------- 1 mol

5.15 g ---------------- x

x = (5.15 x 1)/ 1

x = 5.15 moles

N 14 g --------------- 1 mol

28.87 g ---------- x

x = (28.87 x 1) / 14

x = 2 mol

O 16 g ---------------- 1 mol

16.49 g ----------- x

x = (16.49 x 1) / 16

x = 1.03 moles

4.- Divide by the lowest number of moles

C 4.12 / 1.03 = 4

H 5.15 / 1.03 = 5

N 2 / 1.03 = 1.9 ≈ 2

O 1.03 / 1.03 = 1

5.- Write the empirical formula

C₄H₅N₂O

6 0

4 years ago

If you take Organic Chemistry Laboratory (CHM2211L) you will learn the term reflux. A reaction is considered to be at reflux whe

shutvik [7]

Answer : The temperature of the chloroform will be, $101.67^oF$

Explanation :

First we have to calculate the mass of chloroform.

$\text{Mass of chloroform}=\text{Density of chloroform}\times \text{Volume of chloroform}=1.4832g/ml\times 74.81ml=110.958g$

conversion used : $(1cm^3=1ml)$

Now we have to calculate the temperature of the chloroform.

Formula used :

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = amount of heat or energy = 1.46 kJ = 1460 J (1 kJ = 1000 J)

$c$ = specific heat capacity = $0.96J/g.K$

m = mass of substance = 110.958 g

$T_{final}$ = final temperature = ?

$T_{initial}$ = initial temperature = $25^oC=273+25=298K$

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

$1460J=110.958g\times 0.96J/g.K\times (T_{final}-298)K$

$T_{final}=311.706K$

Now we have to convert the temperature from Kelvin to Fahrenheit.

The conversion used for the temperature from Kelvin to Fahrenheit is:

$^oC=\frac{5}{9}\times (^oF-32)$

As we know that, $K=^oC+273$ or, $K-273=^oC$

$K-273=\frac{5}{9}\times (^oF-32)$

$K=\frac{5}{9}\times (^oF-32)+273$ ...........(1)

Now put the value of temperature of Kelvin in (1), we get:

$311.706K=\frac{5}{9}\times (^oF-32)+273$

$T_{final}=101.67^oF$

Therefore, the temperature of the chloroform will be, $101.67^oF$

5 0

3 years ago

What is the correct electron dot symbol for an alumminum atom in the ground state?

weqwewe [10]

Answer: Aluminum is in group IIIA of the periodic table therefore it has three valence electrons. The symbol for aluminum is Al which will be surrounded by three dots. 2.

Explanation:

7 0

3 years ago

I know how to solve it with D=M/V and M1V1 however the answer isn’t correct. Help me please

lara31 [8.8K]

Answer:

23.28 g of O2.

Explanation:

We'll begin by calculating the mass of hexane. This can obtain as follow:

Volume of hexane = 10 mL

Density of hexane = 0.66 g/mL

Mass of hexane =?

Density = mass /volume

0.66 = mass of hexane /10

Cross multiply

Mass of hexane = 0.66 x 10

Mass of hexane = 6.6 g

Next, we shall write the balanced equation for the reaction. This is given below:

2C6H14 + 19O2 —> 12CO2 + 14H2O

Next, we shall determine the masses of C6H14 and O2 that reacted from the balanced equation. This can be obtained as follow:

Molar mass of C6H14 = (12.01x6) + (1.008 x 14)

= 72.06 + 14.112

= 86.172 g/mol

Mass of C6H14 from the balanced equation = 2 x 86.172 = 172.344 g

Molar mass of O2 = 16x2 = 32 g/mol

Mass of O2 from the balanced equation = 19 x 32 = 608 g

From the balanced equation above,

172.344 g of C6H14 reacted with 608 g of O2.

Finally, we shall determine the mass of O2 needed to react with 10 mL (i.e 6.6 g) of hexane, C6H14. This can be obtained as follow:

From the balanced equation above,

172.344 g of C6H14 reacted with 608 g of O2.

Therefore, 6.6 g of C6H14 will react with = (6.6 x 608)/172.344 = 23.28 g of O2.

Therefore, 23.28 g of O2 is needed for the reaction.

8 0

3 years ago

A concentrated aqueous solution of Pb(NO3)2 is slowly added to 1.0 L of a mixed aqueous solution containing 0.010 M Na2CrO4 and

Oduvanchick [21]

Answer:

This means the amount of PbCrO4 will precipitate first, with a [Pb^2+] concentration of 1.8*10^-12 M

Explanation:

Step 1: Data given

Molarity of Na2CrO4 = 0.010 M

Molarity of NaBr = 2.5 M

Ksp(PbCrO4) = 1.8 * 10^–14

Ksp(PbBr2) = 6.3 * 10^–6

Step 2: The balanced equation

PbCrO4 →Pb^2+ + CrO4^2-

PbBr2 → Pb^2+ + 2Br-

Step 3: Define Ksp

Ksp PbCrO4 = [Pb^2+]*[CrO4^2-]

1.8*10^-14 = [Pb^2+] * 0.010 M

[Pb^2+] = 1.8*10^-14 /0.010

[Pb^2+] = 1.8*10^-12 M

The minimum [Pb^2+] needed to precipitate PbCrO4 is 1.8*10^-12 M

Ksp PbBr2 = [Pb^2+][Br-]²

6.3 * 10^–6 = [Pb^2+] (2.5)²

[Pb^2+] = 1*10^-6 M

The minimum [Pb^2+] needed to precipitate PbBr2 is 1*10^-6 M

This means the amount of PbCrO4 will precipitate first, with a [Pb^2+] concentration of 1.8*10^-12 M

5 0

3 years ago