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3 years ago

(scientific investigations) help please.

Chemistry

1 answer:

Novosadov [1.4K]3 years ago

8 0

I agree with what you've chosen for question two and three.

I would choose C for the fourth question and argue that you shall also go with C for question five.

One of the main ideas about repetition is to have multiple Trials- or independent experiments- for a single independent variable using identical experimental setup. The table presented in option C is the only one among the four choices that allots spaces for measurements from multiple independent experiments.

Hypotheses are predictions of the outcome of a particular experiment. A hypothesis is correct only if it accurately describes the outcome of an experiment. The hypothesis, not the data, would have to be revised if the two doesn't fit. The researcher could keep developing and testing new hypotheses until arriving at a correct one.

Additionally, I would prefer option B over option D in the first question- responses to that question can depends on what your teacher says about the validity of different sources, given that neither B nor D are reliable as sources that one would like to cite in a paper.

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When 6.040 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 18.95 grams of CO2 and 7.759 grams of H

algol [13]

Answer: The empirical formula is $CH_2$ and molecular formula is $C_4H_8$

Explanation:

We are given:

Mass of $CO_2$ = 18.95 g

Mass of $H_2O$ = 7.759 g

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 18.59 g of carbon dioxide, = $\frac{12}{44}\times 18.59=5.07g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 7.759 g of water, = $\frac{2}{18}\times 7.759=0.862g$ of hydrogen will be contained.

Mass of C = 5.07 g

Mass of H = 0.862 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{5.07g}{12g/mole}=0.422moles$

Moles of H= $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.862g}{1g/mole}=0.862moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{0.422}{0.422}=1$

For H = $\frac{0.862}{0.422}=2$

The ratio of C : H = 1: 2

Hence the empirical formula is $CH_2$ .

The empirical weight of $CH_2$ = 1(12)+2(1)= 14 g.

The molecular weight = 56.1 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{56.1}{14}=4$

The molecular formula will be= $4\times CH_2=C_4H_8$

6 0

3 years ago

A) Name the following compounds CH, -CH-CH (i) CH, Br -

liq [111]

Answer:

methyl, ethyl,

Explanation:

that should be the case

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3 years ago

Using the standard enthalpies of formation found in the textbook, determine the enthalpy change for the combustion of ethanol c2

ArbitrLikvidat [17]

Enthalpy of formation is calculated by subtracting the total enthalpy of formation of the reactants from those of the products. This is called the HESS' LAW.
ΔHrxn = ΔH(products) - ΔH(reactants)

Since the enthalpies are not listed in this item, from reliable sources, the obtained enthalpies of formation are written below.
ΔH(C2H5OH) = -276 kJ/mol
ΔH(O2) = 0 (because O2 is a pure substance)
ΔH(CO2) = -393.5 kJ/mol
ΔH(H2O) = -285.5 kJ/mol

Using the equation above,
ΔHrxn = (2)(-393.5 kJ/mol) + (3)(-285.5 kJ/mol) - (-276 kJ/mol)
ΔHrxn = -1367.5 kJ/mol

Answer: -1367.5 kJ/mol

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Vera_Pavlovna [14]

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4 years ago

Name the plant cell organelle where photosynthesis occurs.

Alexeev081 [22]

Answer:

chloroplast organelle

Answer. The photosynthesis process takes place in the chloroplast organelle in the growing tissues. As the chlorophyll pigment is available in the chloroplast organelle which is the main photosynthetic pigment, with the help of the molecules they capture the energy of light.

Explanation:

chloroplasts

In plants, photosynthesis takes place in chloroplasts, which contain the chlorophyll. Chloroplasts are surrounded by a double membrane and contain a third inner membrane, called the thylakoid membrane, that forms long folds within the organelle.

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