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AVprozaik [17]
3 years ago
9

When was copper discovered?​

Chemistry
1 answer:
Vesna [10]3 years ago
3 0

Answer:

9000 BC

Explanation:

Although various copper tools and decorative items dating back as early as 9000 BCE have been discovered, archaeological evidence suggests that it was the early Mesopotamians who, around 5000 to 6000 years ago, were the first to fully harness the ability to extract and work with copper.

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Answer:

Molar mass of vitamin K = 450.56\frac{g}{mol}[/tex]

Explanation:

The freezing point of camphor = 178.4 ⁰C

the Kf of camphor =  37.7°C/m

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the relation between freezing point depression and molality is

Depression in freezing point = Kf X molality

Where

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putting values

2.69°C = 37.7°C/m X molality

molality = 0.0714 mol /kg

molality=\frac{molesofvitaminK}{massofcamphor(kg)}=\frac{moles}{0.025}

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we know that moles are related to mass and molar mass of a substance as:

moles=\frac{mass}{molarmass}

For vitamin K the mass is given = 0.802 grams

therefore molar mass = \frac{mass}{moles}=\frac{0.802}{0.00178}=450.56\frac{g}{mol}

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