Answer:
The Cotton Gin
Explanation:
The cotton gin: A game-changing social and economic invention. On this day in 1793, young inventor Eli Whitney had his U.S. patent for the cotton gin approved, an invention that would definitely have an impact on social and economic conditions that led to the Civil War.
Answer: 10ml
In this question, you are given the liquid medicine concentration (100mg/5ml) and the doses of the medicine that must be taken(200mg). You are asked how much ml of the drug needed. Then the calculation would be:
Volume of drug needed= doses of the drug / drug concentration
Volume of drug needed= 200mg / (100mg/5ml)= 10ml
Answer:
False
Explanation:
Increase in polarity of a molecule leads to higher boiling points. The more polar a molecule is, the higher the energy required to breaks intermolecular forces of attraction hence the higher the boiling point. This is the reason why ionic compounds and compounds having polar covalent bonds in them tend to have high boiling points.
Answer:A cup of household bleach changes the color of your favorite T-shirt from purple to pink. - chemical change
Water vapor in your exhaled breath condenses in the air on a cold day.- physical change
Plants use carbon dioxide from the air to make sugar.- chemical change
Butter melts when placed in the Sun- physical change
Explanation:
A chemical change leads to the formation of a new substance and is not easily reversible. A physical change does not lead to the formation of a new substance and is easily reversible. Physical changes include condensation, melting,etc while a chemical change is a chemical reaction.
Answer:
27.60 g urea
Explanation:
The <em>freezing-point depression</em> is expressed by the formula:
In this case,
- ΔT = 5.6 - (-0.9) = 6.5 °C
m is the molality of the urea solution in X (mol urea/kg of X)
First we<u> calculate the molality</u>:
- 6.5 °C = 7.78 °C kg·mol⁻¹ * m
Now we<u> calculate the moles of ure</u>a that were dissolved:
550 g X ⇒ 550 / 1000 = 0.550 kg X
- 0.84 m = mol Urea / 0.550 kg X
Finally we <u>calculate the mass of urea</u>, using its molecular weight:
- 0.46 mol * 60.06 g/mol = 27.60 g urea
