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3 years ago

I need help ASAP!

1 answer:

8 0

Calcium reacts gently with water to give hydrogen and calcium hydroxide, which is only slightly soluble, thus slows down the reaction.

It will be assumed that hydrochloric acid used is a dilute aqueous solution.

However, calcium reacts with hydrochloric acid to give calcium chloride which is readily soluble in water, and hydrogen, being a typical reaction of relatively active metals with acids.
Ca(s) + 2HCl(aq) -> CaCl2(aq) +H2(g) ↑ + heat

The clues that it is a chemical reaction could be:
- formation of a new substance, gaseous hydrogen
- disappearance of a metallic solid in the solution
- heat formed during the vigorous reaction.

As silver is below hydrogen in the electrochemical series, it will not be expected to react with dilute hydrocloric acid. (however, it dissolves in oxidizing acid such as nitric acid, but not displacing hydrogen as a product).

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A graduated cylinder has a mass of 50 g when empty. When 30 mL of water is added, the graduated cylinder has a mass of 120 g. If

Verdich [7]

Answer:

2.9g/cm^3

Explanation:

We're given that the mass of the system before the rock was added was

120g . The mass after the rock was added was 250g, so the rock's mass is 130g.

The initial volume of water in the graduated cylinder was

30 mL , and the volume after the rock was added read 75mL , so the rock's volume is 45mL

Density = Mass over Volume.

AKA. 130g/45mL

2.9g/cm^3 (rounded)

4 0

3 years ago

A compound is composed of only C, H, and O. The combustion of a 0.519-g sample of the compound yields 1.24 g of CO 2 and 0.255 g

vredina [299]

Answer:

$\large\boxed{\large\boxed{C_3H_3O}}$

Explanation:

1. Calculate the mass of C in 1.24 g of CO₂

$1.24gCO_2\times \dfrac{12.011gC}{44.01gCO_2}=0.3384gC$

2. Calculate the mass of H in 0.255g of H₂O

$0.255gH_2O\times \dfrac{2.016gH}{18.015gH_2O}=0.02854gH$

3. Calculate the mass of O by difference

$0.519g-0.3384g-0.02854g=0.15206g$

4. Convert every mass to number of moles:

C: 0.3384g / (12.011g/mol) = 0.02817 mol

H: 0.02854g / (1.008g/mol) = 0.02831 mol

O: 0.15206g / (15.999g/mol) = 0.009504 mol

5. Divide every number of moles by the least number of moles (0.009504):

C: 0.02817/0.009504 = 2.96 ≈ 3

H: 0.02831 / 0.009504 ≈ 3

O: 0.009504 / 0.009504 = 1

6. Those numbers are the respective subscripts in the empirical formula:

$C_3H_3O$

7 0

3 years ago

Which temperature scale would read the highest number for boiling water? A. Kelvin B. Celsius C. Fahrenheit

White raven [17]

the answer is C.) fahrenheit

mark brainliest :)

6 0

3 years ago

Read 2 more answers

A student investigated how much solid was dissolved in sea water.

SashulF [63]

Answer:

weighing balance/analytical balance

Graduated cylinder/buret

Explanation:

The mass of the evaporating basin could be measured using a weighing balance or an analytical balance. Both are classified as weighing scales but the analytical balance can measure the mass of objects up to 4 decimal places, thus, providing better accuracy in measurement than ordinary weighing balance that can only measure up to 2 decimal places.

In order to measure 50 cm3 of the sea water, a graduated cylinder or a buret can be used. Both equipment can measure up to the same decimal places and, thus, have virtually the same accuracy.

3 0

3 years ago

A solution with a volume of 1.00 l is 0.450 m in ch 3 cooh(aq) and 0.550 m in ch 3 coona(aq). what will the ph be after 0.0800 m

Semenov [28]

Before addition of HCl,

conc. of CH3COOH = 0.450 M
conc. of CH3COONa = 0.550 M

After addition of 0.08 M HCl, following reaction occurs in system:
HCl + CH3COONa ↔ CH3COOH + NaCl

Thus, in reaction system conc. of CH3COOH will increase to 0.53 M (0.08M + 0.450M)
And, conc to CH3COONa will reduce to 0.47 M (0.550M - 0.08M)

Now, conc. of H+ ions = ka $\frac{[acid]}{[conjugated base]}$
where ka = dissociation constant for acid = 10^-5 for Ch3COOH

∴ conc. of H+ ions = $\frac{0.53}{0.47}$
= 1.1277 x 10^-5

Now, pH = -log [H+] = -log (1.1227 x 10^-5) = 4.94

4 0

3 years ago