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4 years ago

How many copper atoms are in 70g of copper

Chemistry

1 answer:

Elanso [62]4 years ago

4 0

Answer:

$n = 6.634\times 10^{23}\,atoms$

Explanation:

The total amount of atoms is found by multiplying Avogradro's Number and the number of moles:

$n = \left(6.022\times 10^{23}\,\frac{atoms}{mol} \right)\cdot \left(\frac{70\,g}{63.546\,\frac{g}{mol} } \right)$

$n = 6.634\times 10^{23}\,atoms$

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What is the molarity of a 0.25-liter solution containing 52 grams of HBr? (1 point)

Pani-rosa [81]

2.6 M hBr

This would be the correct answer.

3 0

3 years ago

One way the U.S. Environmental Protection Agency (EPA) tests for chloride contaminants in water is by titrating a sample of silv

babunello [35]

Answer:

5.0x10⁻⁵ M

Explanation:

It seems the question is incomplete, however this is the data that has been found in a web search:

" One way the U.S. Environmental Protection Agency (EPA) tests for chloride contaminants in water is by titrating a sample of silver nitrate solution. Any chloride anions in solution will combine with the silver cations to produce bright white silver chloride precipitate. Suppose a EPA chemist tests a 250 mL sample of groundwater known to be contaminated with nickel(II) chloride, which would react with silver nitrate solution like this:

NiCl₂ + 2AgNO₃ → 2AgCl + Ni(NO₃)₂

The chemist adds 50 mM silver nitrate solution to the sample until silver chloride stops forming. She then washes, dries, and weighs the precipitate. She finds she has collected 3.6 mg of silver chloride. Calculate the concentration of nickel(II) chloride contaminant in the original groundwater sample. Round your answer to 2 significant digits. "

Keep in mind that while the process is the same, if the values in your question are different, then your answer will be different as well.

First we calculate the moles of nickel chloride found in the 250 mL sample:

3.6 mg AgCl ÷ 143.32 mg/mmol * $\frac{1mmolNiCl_{2}}{2mmolAgCl}$ = 0.0126 mmol NiCl₂

Now we divide the moles by the volume to calculate the molarity:

0.0126 mmol / 250 mL = 5.0x10⁻⁵M

4 0

4 years ago

Mass of 0.432 moles of C8H9O4?

Fiesta28 [93]

Find one mole
8 C = 8 * 12 = 96
9 H = 1 * 9 = 9
4 O = 4 *16 = 64
Total = 169

1 mol = 169 grams.
0.432 mol = x

1/0.432 = 169/x
x = 0.432 * 169
x = 73.0 grams

7 0

3 years ago

Read 2 more answers

How is the preodictable arranged by atomic mass, coloms , and rows

bearhunter [10]

answer:an arrangement of elements in columns, based on a set of properties that repeat from row to row

Explanation:

hope this helps love <3

5 0

3 years ago

Read 2 more answers

Neutral atoms contain equal numbers of A protons and electrons. B protons and neutrons. C electrons and neutrons. D protons, ele

Verdich [7]

Answer:

For 1: The correct answer is Option A.

For 2: The correct answer is Option B.

For 3: The correct answer is Option C.

Explanation:

For 1:

Atomic number is defined as the number of electrons or number of protons that are present in a neutral atom. It is represented as Z.

Z = Atomic number = Number of electrons = Number of protons

Mass number is defined as the sum of number of protons and number of neutrons present in an atom. It is represented as A.

A = Mass number = Number of protons + Number of neutrons

Hence, the correct answer is Option A.

For 2:

The isotopic representation of an atom is: $_Z^A\textrm{X}$

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

We are given:

An isotopic representation of beryllium atom: $_4^9\textrm{Be}$

Thus, the number '4' represents the atomic number of beryllium, number '9' represents the mass number of beryllium atom.

Hence, the correct answer is Option B.

For 3:

In CO compound:

Mass of oxygen = 16 g

Mass of carbon = 12 g

In $CO_2$ compound:

Mass of oxygen = 32 g

Mass of carbon = 12 g

Thus, the ratio of mass of oxygen in $CO_2$ and CO is:

$CO_2:CO=32:16=2:1$

Hence, the correct answer is Option C.

3 0

3 years ago