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34kurt
3 years ago
8

Which sample is a pure substance? zinc oxide sugar dissolved in water pond water soil

Chemistry
1 answer:
PolarNik [594]3 years ago
3 0

Answer:

Its (A) zinc oxide

Explanation:

just took the quiz

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An analytical chemist wants to measure the concentration of lead in drinking water in their building. They dilute 1mL of the sam
lidiya [134]

Answer:

b. 50ppm of Pb

c. 2x10⁻⁴M

j. no

Explanation:

The diluted sample has a concentration of 0.5 ppm of Pb. The sample was diluted from 1mL to 100mL. That means the dilution factor is:

100mL / 1mL = 100

That means, the sample was diluted 100 times from its original concentration.

As diluted sample has a concentration of 0.5ppm, the undiluted sample has a concentration of

0.5ppm×100 = <em>50ppm of Pb</em>

1 ppm means 1x10⁻⁴ % by mass, 50 ppm are 50x10⁻⁴ % by mass

As molar mass of Pb is 207g/mol, molarity of 0.050g / L a(50 ppm) are:

0.050gₓ (1mol / 207g) / 1L = <em>2x10⁻⁴M</em>

<em></em>

Based on EPA regulation, the maximum concentration of Lead in drinking water must be 0.015ppm. That means this water <em>is not safe to drink</em>

6 0
4 years ago
What is the density of a sample of the alloy pewter, (a mixture of tin and copper or lead) if a 7.11 cm3 sample has a mass of 53
xxTIMURxx [149]

Answer:

<h3>The answer is 7.47 g/cm³</h3>

Explanation:

The density of a substance can be found by using the formula

density =  \frac{mass}{volume} \\

From the question

mass = 53.137 g

volume = 7.11 cm³

We have

density =  \frac{53.137}{7.11}  \\  = 7.473558368...

We have the final answer as

<h3>7.47 g/cm³</h3>

Hope this helps you

5 0
4 years ago
How many unpaired electrons would you expect on iron in iron ii sulfide. enter an integer?
zimovet [89]
What are ur answers of the question
5 0
3 years ago
Read 2 more answers
If a class has 120 students and the professor wants to purchase two cookies per student (or 2 coo/stu) he or she will need to bu
klio [65]
60 just divide 120 by 2
7 0
3 years ago
Calculate the formula unit mass of Sodium hydroxide.
Ksivusya [100]

Answer:

MNa=22.989 g/mol.

MO=15.999 g/mol.

MH=1.0079 g/mol

4 0
3 years ago
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