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<p>Jawaban &nbsp;&nbsp;<strong>B. 4,18 g</strong></p><p>&nbsp;</p><p><strong>Pembahasan&nbsp;</strong></p><p>Reaksi setara yg terjadi:</p><p>CaC2 + 2 H2O ——&gt; &nbsp;C2H2 + Ca(OH)2 &nbsp; &nbsp; ΔH=</p><p><i>&nbsp; &nbsp; &nbsp; &nbsp;reaktan &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; produk</i></p><p>&nbsp;</p><p>ΔH = ∑ΔHproduk - ∑ΔHreaktan</p><p>&nbsp; &nbsp; &nbsp; &nbsp;= (-226,74 + (-986,58)) - (-62,7 + 2× (-285,84))&nbsp;</p><p>&nbsp; &nbsp; &nbsp; &nbsp;= -578,94 kJ/mol</p><p>&nbsp;</p><p>Q = m.c.Δt</p><p>&nbsp; &nbsp; = 100 × 4,2 × 90</p><p>&nbsp; &nbsp; = 37,8 kJ &nbsp; ——&gt; <i>panas yg dibutuhkan untuk &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; memanaskan air ke 100°C</i></p><p>&nbsp;</p><p>Mr CaC2 = 64</p><p>&nbsp;</p><p>Massa CaC2 yg dibutuhkan:</p><p>37,8/578,84 × 64 = 4,18 g</p><p>&nbsp;</p><p>&nbsp;</p>