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3 years ago

I need help I don’t understand it and I need it done before the end of today

Chemistry

2 answers:

amm18123 years ago

5 0

Answer:

May be trial 2..................

icang [17]3 years ago

5 0

Your values are very precise, but not accurate.

Precision means how close they are to eachother. All three values are within 0.3g of eachother. They are very precise.

However, each measured value is approximately 5g away from the actual mass. Accuracy is how close your values are to the actual value. This means your values are not very accurate.

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What kind of compounds are soluble in water?

MrMuchimi

The answer should be Ionic Compounds.

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3 years ago

A scientist is performing an experiment on a powder. Which of the following is a sign that a chemical change has definitely occu

n200080 [17]

The powder catches fire. The rest of the choices pertains to physical changes on the powder. When the powder catches fire a chemical change happens. For example, if the powder is organic, carbon dioxide and water will result during the combustion.

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3 years ago

Consider that a sample of a compound is decomposed and the masses of its constituent elements is as follows: 1.443 g Se, 0.5848

sladkih [1.3K]

Answer: The empirical formula is $SeO_2$ .

Explanation:

So, the mass of each element is given:

Mass of Se = 1.443 g

Mass of O = 0.5848 g

Step 1 : convert given masses into moles.

Moles of Se= $\frac{\text{ given mass of Se}}{\text{ molar mass of Se}}= \frac{1.443g}{79g/mole}=0.018moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{0.5848g}{16g/mole}=0.036moles$

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

For Se = $\frac{0.018}{0.018}=1$

For O = $\frac{0.036}{0.018}=2$

The ratio of Se: O = 1: 2

Hence the empirical formula is $SeO_2$ .

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4 years ago

José and Laurel measured the length of a stick's shadow during the day. Without knowing the length of the stick, which of their

vladimir1956 [14]

Answer:

I think in the middle of the day because the sun isn't going down yet

Explanation:

6 0

3 years ago

Which of the following sentences represents a physical change? sugar dissolves in coffee iron rusts gasoline burns in an engine

MAXImum [283]

<u><em>Answer:</em></u>

Physical changes example is sugar dissolves in coffee
Chemical changes examples are iron rusts, gasoline burns in an engine and a candle burns.

Explanation.

Physical changes depend on only physical state, not on composition, which can be separated by physical means while chemical changes depend on composition and only separated by chemical ways.
As in case of iron rusting, gasoline and candle burn are cases chemical changes bcz they convert into another substance whose composition is different from other as compare to sugar which has same composition in coffee ,only state is changed from solid to liquid.

6 0

3 years ago

Read 2 more answers