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2 years ago

the mass number of a chromium Atom is 52 and it has 24 protons. How many neutrons does this atom have?

Chemistry

2 answers:

Luda [366]2 years ago

8 0

Answer:

It has 28 neutrons

Explanation:

Hi, by definition the mass number of an element if given by:

$A=n_{protons}+n_{neutrons}$

Knowing the mass number of chromiun and the amount of protons it has:

$52=24+n_{neutrons}$

$n_{neutrons}=52-24$

$n_{neutrons}=28$

It has 28 neutrons

omeli [17]2 years ago

3 0

Chromium has a total of 28 neutrons. This is found because we subtract the number of protons (the atomic number) from the mass number. 52 minus 24 gives us 28. It also has 24 electrons.

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What are the mole fraction and the mass percent of a solution made by dissolving 0.21 g KBr in 0.355 L water? (d = 1.00 g/mL.) m

IRISSAK [1]

Answer:

Mol fraction H2O = 0.99991

Mol fraction KBr = 0.00009

mass % KBr = 0.059 %

mass % H2O = 99.941 %

Explanation:

Step 1: Data given

Mass of KBr = 0.21 grams

Molar mass KBr = 119 g/mol

Volume of water = 355 mL

Density of water = 1.00 g/mL

Molar mass water = 18.02 g/mol

Step 2: Calculate mass water

Mass water = 355 mL * 1g /mL

Mass water = 355 grams

Step 3: Calculate moles water

Moles water = mass water / molar mass water

Moles water = 355 grams / 18.02 g/mol

Moles water = 19.7 moles

Step 4: Calculate moles KBr

Moles KBr = 0.21 grams / 119 g/mol

Moles KBr = 0.00176 moles

Step 5: Calculate total moles

Total moles = 19.7 moles + 0.00176 moles

Total moles = 19.70176 moles

Step 6: Calculate mol fraction

Mol fraction H2O = 19.7 moles / 19.70176 moles

Mol fraction H2O = 0.99991

Step 7: Calculate mol fraction KBr

Mol fraction KBr = 0.00176 / 19.70176

Mol fraction KBr = 0.00009

Step 6: Calculate mass %

mass % KBR = (0.21 grams / (0.21 + 355) grams) *100%

mass % KBr = 0.059 %

mass % H2O = (355 grams / 355.21 grams) *100%

mass % H2O = 99.941 %

8 0

3 years ago

A stainless steel knife has a volume of 1.2 cubic centimeters and a mass of 9.0 grams.

bija089 [108]

Answer:

7.5

Explanation:

density = mass / volume

9÷1.2 = 7.5

5 0

2 years ago

When calcium metal (Ca) reacts with oxygen gas (O2), it produces the ionic compound calcium oxide (CaO). Write the balanced equa

malfutka [58]

The balanced chemical equation for the reaction is

2Ca(s) + O₂(g) → 2CaO(s)

and

The process meets the requirements to be considered a redox reaction.

From the question,

We are to write a balanced chemical equation for the reaction between Calcium metal and oxygen gas

The balanced chemical equation for the reaction is

2Ca(s) + O₂(g) → 2CaO(s)

This is the balanced chemical equation for the reaction

To determine whether the reaction meets the requirements to be considered a redox reaction,

We will define the term redox reaction

A redox reaction, also called oxidation-reduction reaction, is any chemical reaction in which the oxidation number of a participating chemical species changes.

From the balanced equation above we can observe that the oxidation number of the participating species(Calcium and oxygen) changed.

The oxidation number of Calcium changed from 0 to +2

and

The oxidation number of Oxygen changed from 0 to -2

∴ The process meets the requirements to be considered a redox reaction.

Hence, the balanced chemical equation for the reaction is

2Ca(s) + O₂(g) → 2CaO(s)

and

The process meets the requirements to be considered a redox reaction.

Learn more here: brainly.com/question/17716543

7 0

2 years ago

What is the molarity of a solution composed of 5.85 g of potassium iodide, KI, dissolved

Troyanec [42]

Answer:

0.282 M

General Formulas and Concepts:

Chemistry - Solutions

Reading a Periodic Table
Using Dimensional Analysis
Molarity = moles of solute / liters of solution

Explanation:

Step 1: Define

5.85 g KI

0.125 L

Step 2: Identify Conversions

Molar Mass of K - 39.10 g/mol

Molar Mass of I - 126.90 g/mol

Molar Mass of KI - 39.10 + 126.90 = 166 g/mol

Step 3: Convert

$5.85 \ g \ KI(\frac{1 \ mol \ KI}{166 \ g \ KI} )$ = 0.035241 mol KI

Step 4: Find Molarity

M = 0.035241 mol KI / 0.125 L

M = 0.281928

Step 5: Check

We are given 3 sig figs. Follow sig fig rules and round.

0.281928 M ≈ 0.282 M

7 0

2 years ago

If I make a salt solution that has 1 grams of salt and 9 grams of water the percentage of salt in my solution is _____.

Soloha48 [4]

Answer:

10%

Explanation:

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2 years ago